# Walstad experts? :confused:



## Gold Finger (Oct 13, 2011)

Have not read D. Walstad's book. My guess is that she was not describing an ideal way to keep fish but rather studying how aquaria act if left to their own devices. Perhaps I am wrong. In any case, here's my question. Is there any benefit to minimizing the filter bacteria colony size in my case? I want as low nutrient accumulation as possible. I use a huge bacteria colony which takes a lot of the ammonia and leaves the plants with nothing much to eat besides nitrate. They can get it because I have an anaerobic dirt substrate and fast growing stem plants.


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## Mxx (Dec 29, 2010)

That's not really what the book is about. There are various ways to describe or interpret it I guess. In some sense it is a fresh research based analysis of the natural ecological processes happening in nature and aquariums, which I found very beneficial to read. It also analyzes some of our practices as hobbyists and the challenges resulting from these practices. It does describe one sensible low-tech approach to keeping aquariums, but doesn't claim that is the ideal way. But if you do a natural-planted-tank then there are distinct ways you should set that up which it describes, rather than just leaving it to its own devices. 

As for your actual question, I've been wondering the same thing and haven't been able to find an answer as to how much bio-filtration is optimal. I suppose less might benefit your plants, but you don't want that to be at the expense of the fish, and with every system being different it might be hard to come up with a rule of thumb for that. You could provide excessive bio-media and then have your plants depend upon nitrates, which works but isn't quite as good for them as ammonia of course.


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## DogFish (Jul 16, 2011)

Bio-filtration is limited to how much "food' you offer the bacteria culture to sustain itself. You can't have more than your system can feed. so, if you tank is running properly or in balance you have the right amount.


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## Mxx (Dec 29, 2010)

DogFish said:


> Bio-filtration os limited to how much "food' you offer the bacteria culture to sustain itself. You can't have more than your system can feed. so, if you tank is running properly or in balance you have the right amount.


But bio-filtration can be limited by different factors, one being the food supply, and the other being the amount of surface area they have available to colonize. As long as area to colonize exceeds the available food supply for them, you shouldn't have problems with ammonia or nitrites.


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## Gold Finger (Oct 13, 2011)

Mxx said:


> That's not really what the book is about. There are various ways to describe or interpret it I guess. In some sense it is a fresh research based analysis of the natural ecological processes happening in nature and aquariums, which I found very beneficial to read. It also analyzes some of our practices as hobbyists and the challenges resulting from these practices. It does describe one sensible low-tech approach to keeping aquariums, but doesn't claim that is the ideal way. But if you do a natural-planted-tank then there are distinct ways you should set that up which it describes, rather than just leaving it to its own devices.
> 
> As for your actual question, I've been wondering the same thing and haven't been able to find an answer as to how much bio-filtration is optimal. I suppose less might benefit your plants, but you don't want that to be at the expense of the fish, and with every system being different it might be hard to come up with a rule of thumb for that. You could provide excessive bio-media and then have your plants depend upon nitrates, which works but isn't quite as good for them as ammonia of course.


 What a fantastic answer. Though it does not contain my solution, per se, it is refreshing and helpful, so thank you very much. It gives me a lot to think about and affirms what I am thinking. It is rare that a poster reads a question properly and gives a response to the actual question, especially when they don't have a neat concise solution. I often get a different solution suggested in that case, and it is usually one which does not help at all. 

Anyway, at the risk of repeating myself, back to my question. I suppose that if I give the bacteria all the area they could possibly use and let the plants get by on whatever they can find I may not have the best plant growth, but should have the lowest possible nutrient accumulation, nitrate in particular; remembering that this is my goal. If I am mistaken and my goal would be better achieved by regulating the bacterial colonies by limiting their available area, and anyone knows this to be true, please let me know. 

I am erring on the side of the large bacterial colony as I think such a system would be more stable than a nutrient export technique which depended mainly on plants, as I think plants may vary more in their uptake, having periods of dormancy, and more importantly, because I want them to be forced to use the available nitrate as this is my problem nutrient. Again I am not sure. I have been told that plants will uptake more nutrient than they need and stockpile it, but also know that they prefer ammonia form nitrogen to nitrate which they must convert (with bacterial aid). 

Any thoughts would be appreciated. Thanks!


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## Mxx (Dec 29, 2010)

Thanks, I try!

That's the approach I'm using myself, having a canister filter full of bio-media big enough for a tank several times the size of mine. If the control of problem nitrates is your goal then you might try using Seachem Matrix or similar in your filter as well. 

If you wanted potentially better answers then what we've been able to provide here you might try asking just that question very specifically with a title to match. For it is an important question in our hobby. Make sure to post a link to a new thread here if you do create a new one.


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## DogFish (Jul 16, 2011)

Mxx said:


> ****As long as area to colonize exceeds the available food supply for them, you shouldn't have problems with ammonia or nitrites.


I respectfully disagree, this statement is flawed. 

You can not have more bacteria than food supply, it just doesn't work like that. They colony lives in a rather direct relationship to the food source. It will grow or shrink based on food available. This is why we are concerned about spikes. The bio-filter can't keep up.


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## thefisherman (Oct 15, 2011)

i would also like to add that plants prefer ammonia/ammonium over nitrates. based in walstad's research this is due to "extra work" plants have to do to convert nitrates back into a form they can readily use.

also, surface area of "biological media" in mechanical filtration is only a duplication of where your true biofilter (in a healthy established aquarium) is... your plants and gravel.


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## thefisherman (Oct 15, 2011)

based on my last comment, why are you fixated on nitrates? nitrates are more beneficial to terrestial plants/soils. aquatic plants readily absorb nutrients from the substrate and water column.

walstad's argument is that all the nutrients a plant needs exists in the respiration of fauna, food they eat, poop and plant detritus and mulm.

she outlines the pocessess natural aquatic ecosystems breakdown and deal with waste; coverting and/or releasing nutrients plants use as an end result. therefore she removes the "biological media" in her filters and uses them for circulation purposes only (for gas exchange and nutrient distribution).

again she feels there is no need for this because she understands that the plants (surface area of leaves, stems, roots, etc) and substrates (gravel, driftwood, etc) where bacteria colonize (biofilm matrix containing both aerobic amd anerobic) is the only biological filtration needed.




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## Gold Finger (Oct 13, 2011)

thefisherman said:


> based on my last comment, why are you fixated on nitrates? nitrates are more beneficial to terrestial plants/soils. aquatic plants readily absorb nutrients from the substrate and water column.
> 
> walstad's argument is that all the nutrients a plant needs exists in the respiration of fauna, food they eat, poop and plant detritus and mulm.
> 
> ...


Because I am stocking goldfish; bigger messier fish than work in her system. My nitrates will continue to creep past what the plants need and far past toxic levels for goldfish, which are quite sensitive to levels above 30ppm nitrate. I know levels below this may limit plant growth, but this does not bother me as I don't need plant growth beyond the ability to keep nitrate down. Nitrate is my problem nutrient. If it were not so I would limit my bacterial colony area a la Walstad.

PS. Thanks again. These are all good responses. If I find the answer it may well be here. I hope I have been clear enough and will post a better response later. I am afraid I am too rushed to do so right now.


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## bpb (Mar 8, 2011)

If aquatic plants prefer ammonia to nitrate, which source absorbs ammonia faster in general? The nitrifying bacteria, or the plants themselves? Or is that difference not really measurable?


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## longbeach (Nov 2, 2011)

I agree with thefisherman.

Way back in the 1960's a friend of ours had a 20 gallon tank. It was setup with about 1 1/2 inches of gravel. He had vallesneria in it for plants and about 5 mosquito fish caught locally. The tank got medium light from a nearby window. Nothing else. He occasionally fed the fish. This tank had balanced itself, and I remember that it ran for several years until he moved. I'll never forget how nice it was because at that time my dad and myself were running mechanical tanks, filters and airstones and couldn't achieve the peace, and natural look that his tank had created on it's own. (I assume he did a random cleaning as light syphoning but will never know). No algae and the water was always crystal clear. The tank was left to its own devices and created its own enviroment to survive.

As to stocking your tank with goldfish it could be done but that balance has to be reached with plants and one fish first...then you can increase after giving the tank a chance to develope. Mosquito fish were chosen because they are local fish in our swamps, so no heater was needed either. It would be a great project with nano fish...Gold fish sort of scare me because of the size they can get.


Sorry I don't know all the chemistry to this, but I do know it can and does work.


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## thefisherman (Oct 15, 2011)

bpb said:


> If aquatic plants prefer ammonia to nitrate, which source absorbs ammonia faster in general? The nitrifying bacteria, or the plants themselves? Or is that difference not really measurable?


that's an excellent question... plants AND bacteria both compete for it.


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## thefisherman (Oct 15, 2011)

Gold Finger said:


> Because I am stocking goldfish; bigger messier fish than work in her system. My nitrates will continue to creep past what the plants need and far past toxic levels for goldfish, which are quite sensitive to levels above 30ppm nitrate. I know levels below this may limit plant growth, but this does not bother me as I don't need plant growth beyond the ability to keep nitrate down. Nitrate is my problem nutrient. If it were not so I would limit my bacterial colony area a la Walstad.
> 
> PS. Thanks again. These are all good responses. If I find the answer it may well be here. I hope I have been clear enough and will post a better response later. I am afraid I am too rushed to do so right now.


that's what the forum is for bro, any 2 cents worth of insight or experience I can share to help you make the best decision is yours and my pleasure :smile:

Again I do not understand why you are fixated on Nitrates building up. Is this something that you have already experienced in your tanks? or are you referring to a FO setup? For FO/gravel only, you absolutely need and rely on the nitrifying processes in the bio media of mechanical filters.

but in planted tanks, as walstad says "your plants would remove more total N and prevent nitrate accumulation if your tanks had less biological filtration. This is because plants may accumulate more N in their tissue when it is given to them as ammonium than when it is given to them as Nitrate."

if you DO have a Nitrate accumulation in a heavily planted tank, you may be using an UGF or have soo much circulation in your tank that your substrate becomes too aerobic; which prevents Denitrification [an anaerobic bacterial processes typically occurring in the soil substrate or filters].

As for your goldfish project, i agree with long beach. You will have to balance out the tank with enough plant mass to offset the goldfish's waste... with the specific goal of plants as natural filters. problem is, you goldfish might be eating your natural filters! :O

As far as water clarity in a "natural tank" with no filtration, walstad points out your tank may become tinted yellow over time.


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## bpb (Mar 8, 2011)

thefisherman said:


> that's an excellent question... plants AND bacteria both compete for it.


Oh I definitely understand that. I'm solid on my nitrogen cycle. I guess i am meaning what will consume ammonia faster, the plants, or the bacteria. I know they are both working on it together, but which has a bigger impact on removing ammonia.


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## fermentedhiker (Oct 28, 2011)

Just a thought. Could you setup up your system without any media in your filter? This would give VERY limited surface area for bacterial growth. Then by testing VERY frequently for Ammonia and Nitrite buildup you can tell how much the plants are actually up-taking. Then increase the amount of media in the filter(s) incrementally as needed/indicated by your water tests.

just an idea


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## Gold Finger (Oct 13, 2011)

Mxx said:


> Thanks, I try!
> 
> That's the approach I'm using myself, having a canister filter full of bio-media big enough for a tank several times the size of mine. If the control of problem nitrates is your goal then you might try using Seachem Matrix or similar in your filter as well.
> 
> If you wanted potentially better answers then what we've been able to provide here you might try asking just that question very specifically with a title to match. For it is an important question in our hobby. Make sure to post a link to a new thread here if you do create a new one.


I should have posted this question with a title like "filter bac to plant ratio!?!?", or something like that, and I should have posted it in "filtration" but I am getting good response here and feel weird about splitting the post now. People skim quickly and miss enough info in posts that are not split, so for better or worse I will leave it here.


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## Gold Finger (Oct 13, 2011)

bpb said:


> If aquatic plants prefer ammonia to nitrate, which source absorbs ammonia faster in general? The nitrifying bacteria, or the plants themselves? Or is that difference not really measurable?


 My understanding is that plants _can_ uptake nitrogen quicker than bacteria can as long as they are not inhibited by limiting factors, in other words "in general" and that a bac colony takes 24 hours to double it's size which is the only way it can increase it's uptake, so plants can also respond to a spike more quickly, in general. I may well be wrong here, and it may be an illogical comparison in any case; apples to oranges. How do you quantify-ably compare a colony of billions of minute creatures to several plants, in order to determine which is faster at something?


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## Gold Finger (Oct 13, 2011)

thefisherman said:


> that's what the forum is for bro, any 2 cents worth of insight or experience I can share to help you make the best decision is yours and my pleasure :smile:
> 
> Again I do not understand why you are fixated on Nitrates building up. Is this something that you have already experienced in your tanks? or are you referring to a FO setup? For FO/gravel only, you absolutely need and rely on the nitrifying processes in the bio media of mechanical filters.
> 
> ...


First, like I said in my opening post, I have an anaerobic dirt substrate with fast growing stems not a fish only tank.

Second, I am concerned with nitrate accumulation because I believe that goldfish are extremely sensitive to it and that it stunts them. My fish is two years old and well over five inches and at this rate may well end up near a foot long. 

Third, I have been advised that I would need to fill my 70 gallon with so many plants the fish could barely swim if I went plant only


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## Gold Finger (Oct 13, 2011)

fermentedhiker said:


> Just a thought. Could you setup up your system without any media in your filter? This would give VERY limited surface area for bacterial growth. Then by testing VERY frequently for Ammonia and Nitrite buildup you can tell how much the plants are actually up-taking. Then increase the amount of media in the filter(s) incrementally as needed/indicated by your water tests.
> 
> just an idea


I could. That would be Walstad's approach. I have no reason to go that far down that road, though. I am asking if there might be any benefit to going half way there and just limiting my bacs a bit.

I won't rely totally on plants because my bioload will become very high, so A) it is better to have bacs convert some ammonia than not, and B) When a plant only system reaches it's limit the resultant toxin is ammonia, but when a system involving additional bacteria reaches it's limit the resultant toxin is nitrate, which is much less toxic.


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## Gold Finger (Oct 13, 2011)

Mxx, I think you summed it up very nicely when you said this ( which I edited for space)


Mxx said:


> I suppose less (bio filter media surface area) might benefit your plants, but you don't want that to be at the expense of the fish... You could provide excessive bio-media and then have your plants depend upon nitrates, which works but isn't quite as good for them as ammonia of course.


In which case, no, there is no reason for me to limit my bac area since my fish health is more important to me than my plant health. For what it is worth, it is what I believe at this point.

However, Thefisherman says, and I Quote: that walstad says "your plants would remove more total N and prevent nitrate accumulation if your tanks had less biological filtration. This is because plants may accumulate more N in their tissue when it is given to them as ammonium than when it is given to them as Nitrate."

This is the "reason" to limit that I was asking about.

Both points are relevant and quite astute.

Moving forward, I do not believe that Walstad's described method is best for overstocked tanks. I think massive bio filtration supported by nutrient limited- nitrate scrounging plants probably is.

Comments?


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## plantbrain (Dec 15, 2003)

Mxx said:


> As for your actual question, I've been wondering the same thing and haven't been able to find an answer as to how much bio-filtration is optimal.
> [/qupote]
> 
> This would be highly dependent on the fish loading, feeding, current supplied, plant biomass etc.
> ...


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## Gold Finger (Oct 13, 2011)

Thank you. I will keep my bio unlimited and consider upping my CO2/light if I ever show unacceptable nutrients/nitrates, and beyond that, (god forbid) limit my feeding. Growing out my fish is really important to me and I may easily push that factor too hard. Of all the factors at play in optimizing filtration, limiting the excess garbage going into the system is the best way to ease any potential burden on the system. It is something I needed to be reminded of. The big picture is complex and it can be hard for me to keep it all in mind at once. So, thanks again. Thank you all. 

Of course this answer leads to another question.... How do you get the most fish growth with the least food?


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## plantbrain (Dec 15, 2003)

Gold Finger said:


> "your plants would remove more total N and prevent nitrate accumulation if your tanks had less biological filtration. This is because plants may accumulate more N in their tissue when it is given to them as ammonium than when it is given to them as Nitrate."
> 
> This is the "reason" to limit that I was asking about.
> 
> ...


I agree, the plants will assimilate more in their tissue if the sourc eif NH4, they have no choice if they take in NH4........it's Highly toxic to plants, and there are herbicides that use this, and NH4 burn plants.

NO3 on the other hand can be stored in the vacuole in quite considerable amounts to be used for osmoregulation, N for proteins etc. It has more uses.
A balance of both is what is naturally present in every aquarium, but there might be more NH4 relative to NO3.
I'd not worried much about it.

I've dosed NH4 a fair amount to the water, you'd likely better off enriching the sediment if better growth is the goal.


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## plantbrain (Dec 15, 2003)

Gold Finger said:


> Thank you. I will keep my bio unlimited and consider upping my CO2/light if I ever show unacceptable nutrients/nitrates, and beyond that, (god forbid) limit my feeding. Growing out my fish is really important to me and I may easily push that factor too hard. Of all the factors at play in optimizing filtration, limiting the excess garbage going into the system is the best way to ease any potential burden on the system. It is something I needed to be reminded of. The big picture is complex and it can be hard for me to keep it all in mind at once. So, thanks again. Thank you all.
> 
> Of course this answer leads to another question.... How do you get the most fish growth with the least food?


Better assimilation, better digestion in the food, better variety, live foods, flash frozen food vs poorly frozen, machine dried flake food processing vs sun drying, all these lead to better nutritional value, but added cost.


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## Gold Finger (Oct 13, 2011)

This is exactly what I wanted to know... and more. I am sure many besides myself will benefit from reading this thread. Now I am off to research goldfish nutritional assimilation.


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## xjasminex (Jul 26, 2011)

Hey goldfinger! 
You have been busy and I have been keeping up with this thread with interest!
The gab has a good section on goldfish nutrition! Even has recipes for homemade gel food, that's what I feed my fish and I think it is very good for them!


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## Mxx (Dec 29, 2010)

Quite a productive discussion! In my humble opinion, I believe we might be looking at it in the wrong manner if we're thinking that bacteria colonies have to increase in size to keep up with plants in terms of absorbing nitrogens. Ammonia is produced in our tanks on a steady and continual basis, and bacteria and plants will both be feeding on it continuously. Whether one is a bit more effective than the other I'm not sure, but surely they'll both be consuming some at least. And the bacteria population should stay at more or less a stable size throughout in relation to both the food source and so long as they have non-limiting area to colonize as well. (Do plants consume nitrogens at night by the way?) 

I'd however certainly like to know which one consumes more, even if it is a difficult question to answer. One hobbyist reported switching a mature filter to a new tank to cycle it, but then suffered casualties which turned out to be because of an ammonia spike. He suggested that this demonstrated that his plants were absorbing everything as evidenced by his bio-media being devoid of bacterial colonies. That was one potential example, which is however less than definitive. 

The thing I was worried about was that if my tank happened to be depleted in any one of the other 16 nutrients which plants require, then does that essentially stop their ability to metabolize properly and absorb nitrogens? That's my real worry in trying to rely primarily for filtration. 

Good to have Barr weigh in here as well. I was asking him about his client's 1600 gallon tank as that seemed like potentially massively excessive bio-filtration as well considering the enormous plant mass that tank contained. So it's good to get a bit more clarification on such matters now!


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## thefisherman (Oct 15, 2011)

when plantbrain talks.. i listen. its a pleasure to be a part of this discussion gentlemen 


Sent from my iPhone


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## Gold Finger (Oct 13, 2011)

xjasminex said:


> Hey goldfinger!
> You have been busy and I have been keeping up with this thread with interest!
> The gab has a good section on goldfish nutrition! Even has recipes for homemade gel food, that's what I feed my fish and I think it is very good for them!


 Yeah, I have read their recipes but never actually made gel food. If I ever do I will definitely want to pick your brain


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## plantbrain (Dec 15, 2003)

Mxx said:


> Quite a productive discussion! In my humble opinion, I believe we might be looking at it in the wrong manner if we're thinking that bacteria colonies have to increase in size to keep up with plants in terms of absorbing nitrogens. Ammonia is produced in our tanks on a steady and continual basis, and bacteria and plants will both be feeding on it continuously. Whether one is a bit more effective than the other I'm not sure, but surely they'll both be consuming some at least. And the bacteria population should stay at more or less a stable size throughout in relation to both the food source and so long as they have non-limiting area to colonize as well. (Do plants consume nitrogens at night by the way?)
> 
> I'd however certainly like to know which one consumes more, even if it is a difficult question to answer. One hobbyist reported switching a mature filter to a new tank to cycle it, but then suffered casualties which turned out to be because of an ammonia spike. He suggested that this demonstrated that his plants were absorbing everything as evidenced by his bio-media being devoid of bacterial colonies. That was one potential example, which is however less than definitive.
> 
> ...


There is a rather straight forward Research method that tells where each of the N's go and what is the done to them through time, N15 stable isotope tracers.

You'd need N14H4 and N15O3 and dose those and then take bacteria and plant samples(algae too), then measure the N15 to see who got what.

Most Universities have such facilities.

Getting the N15 is the hard part and being allowed to add it to anything but a sealed closed system like an aquarium etc.


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## plantbrain (Dec 15, 2003)

Mxx said:


> (Do plants consume nitrogens at night by the way?)


Yes



> I'd however certainly like to know which one consumes more, even if it is a difficult question to answer. One hobbyist reported switching a mature filter to a new tank to cycle it, but then suffered casualties which turned out to be because of an ammonia spike. He suggested that this demonstrated that his plants were absorbing everything as evidenced by his bio-media being devoid of bacterial colonies. That was one potential example, which is however less than definitive.


New planted tanks correctly set up never have any measured NH4.
No cycling occurs, a silent cycle perhaps.



> The thing I was worried about was that if my tank happened to be depleted in any one of the other 16 nutrients which plants require, then does that essentially stop their ability to metabolize properly and absorb nitrogens? That's my real worry in trying to rely primarily for filtration.


According to Liebig's law, yes.

This applies to aquatic horticulture and causes a lot of correlative issues that many seem to think shows "evidence" say....like PO4 limitation help cure algae.



> Good to have Barr weigh in here as well. I was asking him about his client's 1600 gallon tank as that seemed like potentially massively excessive bio-filtration as well considering the enormous plant mass that tank contained. So it's good to get a bit more clarification on such matters now!


Tank works the same as the smaller ones, but tends to have less flow really to smaller comparative tanks.


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## xjasminex (Jul 26, 2011)

Goldfinger, I have only made it once, and it is going to last me forever....but my goldfish love it and I think their color is very vibrant, I hardly feed them flake food, just what I have left from before the gel, along with fresh kale on a daily basis and supplemented with what ever else I can get them to eat, like oranges and sweet potatoes.


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## Gold Finger (Oct 13, 2011)

I think I should consider feeding four times a day instead of two, to improve assimilation. Whadda ya think? Also. I am a big fan of probiotics in human diet as an assimilation aid. Are you familiar with Saki Hikari's proprietary probiotic bacteria, "Hikari Germ" or any others, and do you have any faith it it/them?


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