# Is phosphate causing algae?



## Anubis_stat (Aug 25, 2021)

I have a 58 gallon aquarium set up in February that I have been having green algae problems with.

Heavily planted, Co2 running. Lights are on 8 hours a day, Co2 comes on one hour before they are on and shuts off one hour before they go off. One canister filter rated for up to 50 gallon and one HOB filter rated for up to 60 gallons.

Temp 78-80F
Current parameters are as follows:
pH 6.8
Ammonia 0
Nitrite 0
Nitrates 5.0
Phosphate 2

I also tested my tap water and the phosphate is reading 2-5 ppm from the tap. I just purchased the phosphate test today to see if that was my problem.

I feed 3 small meals a day that are consumed entirely within 2 minutes, I have an automatic feeder. I also supplement with a variety of frozen and bottom tabs for my corys. I have a cleanup crew of 2 ghost shrimp, 6 corys, and 6 nerite snails. I do a roughly 50% water change weekly, and I rinse my media off in old tank water at that time and stir/vacuum the gravel. I was dosing seachem flourish once a week during water change, but I've switched to twice a week smaller dosing. I also have root tabs I've replenished at the 2-3 month mark. 

Is it the phosphate giving me the algae problems? I know plants require phosphate but I've also read any thing over 1 can cause blooms. I know the tap water matches what's in the tank so it seems as if it's coming from the tap, however I have an axolotl tank and a heavily planted betta tank and neither of them have any algae.

This is directly from my tap


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## vanostav61 (May 8, 2020)

Can you get the tap water quality report from your suplier? I wonder what else is there in your water, specifically the Iron content.


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## Anubis_stat (Aug 25, 2021)

vanostav61 said:


> Can you get the tap water quality report from your suplier? I wonder what else is there in your water, specifically the Iron content.


This is all the city reports


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## vanostav61 (May 8, 2020)

I hoped the water report would shed some light but that didn't happen.

Generally speaking the 2ppm PO4 is in the high range but it's not critical. I don't think this is the root cause of your algae.

What light fixture are you using?


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## Anubis_stat (Aug 25, 2021)

vanostav61 said:


> I hoped the water report would shed some light but that didn't happen.
> 
> Generally speaking the 2ppm PO4 is in the high range but it's not critical. I don't think this is the root cause of your algae.
> 
> What light fixture are you using?


This one, blue is at the highest setting of the 6 settings and white is turned one or two settings down

https://www.amazon.com/dp/B07V8GPZ3...abc_72M3V2JP984FY84FDV02?_encoding=UTF8&psc=1


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## vanostav61 (May 8, 2020)

Your light is very low considering you are supplying CO2. You should bring back the white light to full brightness. Ideally you would need two of these fixtures to get somewhere in the mid light range.

Your Nitrogen level is low especially in comparison to your Phosphate level. Usually the proportion should be 10:1 meaning to every 10ppm of NO3 there should be 1ppm PO4. So you should bring up your NO3 to about 20ppm.

Continue dosing the Flourish but in the future you should better get some CSM+B and mix the fertilizer by your self with the addition of some Magnesium.

Trim out any badly affected leaves, any yellow dying leaves. Add some snails, 5-10 snails won't hurt having in there.


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## AquaPlants (Mar 22, 2014)

I have the same amount of PO4 as you here in GA, out of my tap. I had green hair algae and of bit BBA for a month. I trimmed and removed as much as I could, added a UV, and cut lighting down to 4 hours for a week. I added 6 SAE’s, and some snails. I also added an additional smaller paintball CO2 tank using a bubble diffuser on top of my 5 pound that goes into a CO2 reactor. I’ve read that micro CO2 bubbles hitting the actual plants is also a benefit apparently so I thought I’d give it a try and it seems to be working out well. It’s been more than a month now and I don’t see anymore algae so far. I’m also dosing thrive half the recommended amount 3 times a week and the plants are responding well!


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## Anubis_stat (Aug 25, 2021)

vanostav61 said:


> Your light is very low considering you are supplying CO2. You should bring back the white light to full brightness. Ideally you would need two of these fixtures to get somewhere in the mid light range.
> 
> Your Nitrogen level is low especially in comparison to your Phosphate level. Usually the proportion should be 10:1 meaning to every 10ppm of NO3 there should be 1ppm PO4. So you should bring up your NO3 to about 20ppm.
> 
> ...


Thank you. I had another lamp on there and full light but was worried too much light was causing the algae so backed off a few weeks ago. I can increase it again.

I typically don't worry much with my nitrates getting to 20-30 on my other tanks, but I have a few rams in this tank and this is my first time keeping them. I had read that they were very sensitive to nitrate and it should always be kept below 10.

I trimmed some leaves last water change but definitely see a few more I need to go in and tackle. I have 6 nerite snails already.


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## vanostav61 (May 8, 2020)

Did it get any better when you removed the other light?

If you can't increase the NO3 then you will have to reduce the PO4 and that's going to be more complicated.


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## Anubis_stat (Aug 25, 2021)

vanostav61 said:


> Did it get any better when you removed the other light?
> 
> If you can't increase the NO3 then you will have to reduce the PO4 and that's going to be more complicated.


I would say it's about the same. There's maybe less build up on the glass but it still shows up 2-3 days after cleaning it off, and the amount on the leaves is not diminishing.

I can decrease my water changes, currently I do them so frequently because I didn't want any detrimental effects for my rams. I think extending out to 30% every other week would help bring my nitrates up.


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## Anon (Mar 16, 2014)

Hi @Anubis_stat 



Anubis_stat said:


> I also tested my tap water and the phosphate is reading 2-5 ppm from the tap.


That range is about 10X higher than I would want in my tanks. And, as your tap water is already high in phosphate, tank water changes isn't going to be the answer. Could you use rainwater or RO+DI water to dilute your tap water? Also, be aware that test kits can only detect inorganic phosphate (orthophosphate) - they are unable to detect organophosphates.

You could consider using a product such as _Seachem PhosGuard._

Anon

Hi @Anubis_stat 

Further to my previous reply, I think the answer to the question you posed is that phosphate is almost certainly _contributing_ to the algae that you are seeing in your tank.

Anon


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## Goodwood (May 5, 2021)

Do you actually feed 3 times a day? Or is that supposed to be 3x a week?


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## Fat Guy (Nov 19, 2003)

Anubis_stat said:


> Thank you. I had another lamp on there and full light but was worried too much light was causing the algae so backed off a few weeks ago. I can increase it again.


^^^^This is your main problem ^^^ 


you had too much light over your tank to begin with. for the love of the plant gods do not listen to the previous comment about increasing your lighting to fix this algae problem. You did the right thing in the first place by reducing the lighting but you need to have more patience. those plant leaves aren’t going to magically revitalize in two weeks. They need to be removed. You had two lighting units running full blast over slow growing plants. Your tank went out of whack because of this and your plants were affected by it and the algae took over.

It’s not the phosphates in your tapwater or the phosphate reading in your tank. If you’re feeding your fish three times a day then you are definitely overfeeding and contributing to the organic waste in the tank however again your main issue is your lighting and that needs to be reduced and you need to trim all the plant leaves that have the algae and give them a chance to grow new healthy leaves. Also just to be clear you mentioned that your tank was heavily planted. No offense but this is a lightly planted tank IMHO.

Reduce the light, reduce the feeding, Trim the leaves and be patient…or rip out the severely affected plants and replace with healthy ones and start over.

good luck!


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## vanostav61 (May 8, 2020)

Fat Guy said:


> ^^^^This is your main problem ^^^
> 
> 
> you had too much light over your tank to begin with. for the love of the plant gods do not listen to the previous comment about increasing your lighting to fix this algae problem. You did the right thing in the first place by reducing the lighting but you need to have more patience. those plant leaves aren’t going to magically revitalize in two weeks. They need to be removed. You had two lighting units running full blast over slow growing plants. Your tank went out of whack because of this and your plants were affected by it and the algae took over.
> ...


You really believe his cheap 25W fixture provides enough light for a 60 Gallon deep tank with CO2 ?

Wow ...


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## WaldoDude (Jul 4, 2019)

Im pretty sure Im having the exact same problem!!! Phosphates in RO/DI water? - problems with algae
Your pictures look very similar to mine. I've got phosphates somewhere between 2-5ppm and problem seems to be phosphates in my rodi water but ive yet to confirm that 100% by testing some distilled water (new lockdown here). Additionally my nitrates were also low, in my case close to 0ppm. From what I've been told phosphates isnt necessarily a problem (unless super high) if you have sufficient amount of the other nutrients such as nitrates. So since I can't seem to reduce my phosphates I've started dosing nitrates (seachem nitrogen) and trying to maintain levels at 5ppm. I didn't know about the 10:1 ratio so maybe I need more? I also increased my lights to my pre-algae settings. I've still got the algae but certain plants have started growing again, so some progress but this is only week 2 since these changes so we'll so how it goes.


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## Greggz (May 19, 2008)

IMO of all the comments so far I would listen to @Fat Guy.

FWIW, here are my thoughts.

Before you make changes based on readings, take the time to calibrate your PO4 kit. Many times the reading is off and people make changes based on false assumptions.

You say your tank is heavily planted but in reality it is very lightly planted. And the plants you have need very little light and nutrients. Do not add more light unless you plan on adding more fast growing stems and densely planting the tank.

Three meals a day is likely contributing to your issue. Overfeeding results in an excess build up of organics. And you say you also add frozen food and bottom tabs for Cory’s as well. Frozen food should be fed very sparingly and should be thawed and rinsed. It’s a major contributor to dirty tank conditions.

In general fish require MUCH less food than most provide. If someone were to see how little I feed my tank fully of hungry Rainbowfish they would be shocked. Yet fish are very healthy and long lived. You create more problems overfeeding than underfeeding.

There is no magic NO3 : PO4 10:1 ratio. In fact, most of the best tanks in the world are closer to 3:1 and 2:1. 2 ppm PO4 is not in a high range, and PO4 is not causing your algae. The best tanks dose PO4 to get higher than that. And do not use Phosguard. There isn’t a successful planted tank in the world that needs it.

Do not perform less water changes to raise NO3. If anything, perform MORE larger water changes and dose NO3. There is a world of difference between a tank that is generating nutrients from fish waste/feeding than an uber clean tank that is dosed with nutrients.

You say you have CO2 running. What does that mean? How much pH drop from fully degassed? Dialing in CO2 correctly can cure a LOT of problems.

And lastly have patience. When you make changes it can take weeks/months to fully understand the effect. Plants take time to transition to new conditions.

Good luck and I look forward to seeing how things go from here.


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## Socratic monologue (Dec 8, 2008)

Trying to interpret that color chart above makes me want to go give my Hanna PO4 checker a big hug. I can't imagine trying to troubleshoot things like this with such poor data -- the color in the tube isn't on the chart. Seriously, the Hannah checker is wonderful.

If you're in a municipality that adds phosphate to the water (I used to live in Minneapolis, and worked at a LFS there, so got a good understanding of this), getting yourself a decent RODI system would help you dial things in. You can start with water of known makeup (two Hs, one O) and add what you need from there.


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## Fat Guy (Nov 19, 2003)

vanostav61 said:


> You really believe his cheap 25W fixture provides enough light for a 60 Gallon deep tank with CO2 ?
> 
> Wow ...


Yup. Take another gander at what they posted. He/She was running TWO lighting units full blast over these undemanding plants in their lightly planted tank. The OP made the right decision when they switched to running just one lighting unit on their path to addressing the algae problem they are experiencing. Telling them to up their lighting before addressing their organic waste issue is like throwing fuel on the fire here. Again, as I had mentioned before, and as Greggz also addresses- when you overfeed like they are, there is an excess build up in organic waste which becomes a large contributing factor to the algae issues they are experiencing. Unfortunately I think you are making things a lot more complicated than they should be with your advice and your untoward sarcasm. “Wow” right back atcha bud.



Greggz said:


> IMO of all the comments so far I would listen to @Fat Guy.


Thank you Greggz. I agree with your comments as well here.


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## vanostav61 (May 8, 2020)

If there is one thing true about this hobby then it's the fact that you can have 100 people with 100 different opinions. What I don't like is when someone comes with "Hey, don't listen to that guy, listen to me". Ok, whatever...

@Anubis_stat, you asked for help and you got a bunch of opinions. Which route to take is up to you.

Love and peace everyone!


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## Greggz (May 19, 2008)

vanostav61 said:


> If there is one thing true about this hobby then it's the fact that you can have 100 people with 100 different opinions.


I agree you can get loads of conflicing information in this hobby. I am sure it is difficult for someone newer to the hobby to wade through. 

The best advice I can offer to anyone is to seek out tanks that demonstrate success in a style similar to what they have mind. Then study their methods. Reach out and ask questions. It's easily the fastest route to success.

One of the problems is that there are many who are eager to repeat what they have read, but have littlle practical experience or success. So stick to people who can show you something you want to emulate. When you do, you begin to realize they have many things in common.

And even then each tank is unique and there will still be a period of trial and error. But getting the basics right sure does help make that process much easier.


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## Deanna (Feb 15, 2017)

Greggz said:


> One of the problems is that there are many who are eager to repeat what they have read, but have littlle practical experience or success. So stick to people who can show you something you want to emulate. When you do, you begin to realize they have many things in common.


Be careful about such conclusions: it implies that education cannot occur unless the educator has personal experience with the subject. This would eliminate almost the entire school system in the Country. Additionally, personal experience is generally anecdotal and very risky in terms of providing repeatable outcomes. The passing on of reliable knowledge, assuming it’s reliable, is among the better ways to learn.

I agree with the rest of your comments and, particularly, found post #16 right on target, but that one paragraph rubs me the wrong way.


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## Greggz (May 19, 2008)

Deanna said:


> Be careful about such conclusions: it implies that education cannot occur unless the educator has personal experience with the subject. This would eliminate almost the entire school system in the Country. Additionally, personal experience is generally anecdotal and very risky in terms of providing repeatable outcomes. The passing on of reliable knowledge, assuming it’s reliable, is among the better ways to learn.
> 
> I agree with the rest of your comments and, particularly, found post #16 right on target, but that one paragraph rubs me the wrong way.


As sometimes happens, we will have to agree to disagree.

In my opinion, seeking out successful people and studying their methods is easily the best way to increase the odds of success. 

There are loads of people who repeat old wives tales because it's what they have read. Iron turns plants red, glut is CO2, PO4 causes algae, micros & macros can't be dosed on the same day, low dKH causes pH crash, NO3 : PO4 must be at 10:1, etc. etc. How should one weight those types of comments? In my opinion by seeing results. 

If someone can demonstrate success, I am very curious to learn more about their methods. If not, I tend to give their comments the weight they deserve. You my friend are an outlier. I've never seen your tank but I value your opinion and look forward to reading your comments. But that is pretty rare indeed.


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## LidijaPN (Jan 15, 2022)

I barely have anything to add to this debate which is way over my head technically, but I was recently told by LFS my y phosphates were way too high (apparently they are high out of the tap here) and seeing them they assumed I was having algae problems.... but my poorly lit 29g is weirdly algae free, and my weird mix of undemanding plants is growing steadily in my very dinky low tech setup.... 

I feel like getting the right balance of things in this hobby is more alchemy than a straight formula...

Of course I might wake up to a bloom tomorrow hahah


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## Greggz (May 19, 2008)

LidijaPN said:


> I barely have anything to add to this debate which is way over my head technically, but I was recently told by LFS my y phosphates were way too high (apparently they are high out of the tap here) and seeing them they assumed I was having algae problems.... but my poorly lit 29g is weirdly algae free, and my weird mix of undemanding plants is growing steadily in my very dinky low tech setup....
> 
> I feel like getting the right balance of things in this hobby is more alchemy than a straight formula...
> 
> Of course I might wake up to a bloom tomorrow hahah


In general I would not be getting my planted tank advice from the LFS. While many are great people they rarely know much if anything about our hobby.

PO4 causing algae was a popular thing to say decades ago. It's been disproven over and over. Plants love PO4. Old myths die hard!


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## Asteroid (Jul 26, 2018)

It's funny because all planted tanks should have some PO4, so why doesn't every planted tank have algae? If the PO4 is truly the "cause" of algae it shouldn't matter what else is going on in the setup as long as there is light. You could follow hobbyists who share their parameters and see what their PO4 levels are and see the results. I normally dose full EI and don't even have fast growing stems so my macro numbers are always on the high side, yet no algae. I'm so confident that high macros don't cause algae that from time to time I put something into my main tank that has some algae on it (might be from a neglected grow out tank or something) and nothing happens, the algae just slowly disappears over time. 

To me the issue is purely in the uptake of organics. Constant uptake via healthy plants removes toxins before they linger. When these toxins are removed any potential algae is deprived of it's food source. Tanks with lots of plants and little livestock always are the easiest to keep clear of algae and tanks with a little bit of plants and lots of livestock are the hardest regardless of PO4 levels.


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## Greggz (May 19, 2008)

Asteroid said:


> To me the issue is purely in the uptake of organics. Constant uptake via healthy plants removes toxins before they linger. When these toxins are removed any potential algae is deprived of it's food source. Tanks with lots of plants and little livestock always are the easiest to keep clear of algae and tanks with a little bit of plants and lots of livestock are the hardest regardless of PO4 levels.


I find this to be true as well. Some recent events have confirmed this even more. I'll be posting an update on this soon.


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## LidijaPN (Jan 15, 2022)

Greggz said:


> In general I would not be getting my planted tank advice from the LFS. While many are great people they rarely know much if anything about our hobby.
> 
> PO4 causing algae was a popular thing to say decades ago. It's been disproven over and over. Plants love PO4. Old myths die hard!


So you’re saying ditch the phosguard and let phosphate be high?


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## Asteroid (Jul 26, 2018)

LidijaPN said:


> So you’re saying ditch the phosguard and let phosphate be high?


@Greggz using/recommending phosguard would be the equivalent to him using plastic plants. He would be ostracized from the planted tank community.


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## LidijaPN (Jan 15, 2022)

Asteroid said:


> @Greggz using/recommending phosguard would be the equivalent to him using plastic plants. He would be ostracized from the planted tank community.


Lol I guess I get away with it because newb haha


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## Asteroid (Jul 26, 2018)

LidijaPN said:


> Lol I guess I get away with it because newb haha


Yep, you newbies can do almost anything, nobody will judge you. So go for it.


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## LidijaPN (Jan 15, 2022)

Asteroid said:


> Yep, you newbies can do almost anything, nobody will judge you. So go for it.


I need to bask in this freedom while it lasts 😅


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## Asteroid (Jul 26, 2018)

LidijaPN said:


> I need to bask in this freedom while it lasts 😅


Yes, definitely enjoy it!


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## Greggz (May 19, 2008)

LidijaPN said:


> So you’re saying ditch the phosguard and let phosphate be high?


I'm curious.....what level of PO4 is in your tap? And how are you testing it??


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## LidijaPN (Jan 15, 2022)

Greggz said:


> I'm curious.....what level of PO4 is in your tap? And how are you testing it??


Oh so I went to the LFS to get my water tested because I was losing fish and my test kit hadn't arrived yet.... and they could find nothing wrong with the water.... and the guy randomly also tested for phosphate and told me 'wow your phosphate is pretty high, but that's not weird, we get high phosphate from the tap here in Montreal. You should use phosguard.'

So I was like wait but my plants like it? And he was like well if you have more than the plants can consume - and I guess you do since it's showing up here - it will lead to algae bloom.

So I was like is there anything else I can do except phosguard? And he was like not really.

And I was like ok here's 17$ I guess.

So I don't know the exact number and he might have just done it to sell the phosguard, I really don't know. What I do know is that I do not have any algae at the moment. But who am I to say I won't get some tomorrow. Way too new at all this to be able to make that judgment call.

People over in the fish losing debate thread have suggested I should, on top of testing for the regular stuff plus the gh and kh - all of which I now have kits for - also test for phosphate, iron and potassium..... but it's all feeling a bit overwhelming at the moment honestly. Like I don't entirely know what those things do.


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## Greggz (May 19, 2008)

LidijaPN said:


> Oh so I went to the LFS to get my water tested because I was losing fish and my test kit hadn't arrived yet.... and they could find nothing wrong with the water.... and the guy randomly also tested for phosphate and told me 'wow your phosphate is pretty high, but that's not weird, we get high phosphate from the tap here in Montreal. You should use phosguard.'
> 
> So I was like wait but my plants like it? And he was like well if you have more than the plants can consume - and I guess you do since it's showing up here - it will lead to algae bloom.
> 
> ...


I don't know of a planted tank in the world that would benefit from Phosguard. And the fish don't care.

What level are we talking about??


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## LidijaPN (Jan 15, 2022)

Greggz said:


> I don't know of a planted tank in the world that would benefit from Phosguard. And the fish don't care.
> 
> What level are we talking about??


I hadn't asked him for a specific number as at that point I had no idea what would be considered high or low (still don't frankly). I can ask him again when I go next time? Do you think it will harm the plants? I haven't seen any slowing of growth but maybe it happens over a longer period..... Also I asked him 'how big a piece should I put in?' and he was like 'whatever will fit in the available space you have in the filter'. Which to me sounded a bit..... sus. Like how much do I need to get rid of the appropriate amount of phosphate? "Oh I don't know... A chunk.'

So I put in a 5x12cm piece.


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## ElleDee (May 16, 2020)

@LidijaPN FWIW, I don't think getting tests for phosphate, iron, and potassium are needed in most cases, particularly in a low tech tank.


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## Greggz (May 19, 2008)

ElleDee said:


> @LidijaPN FWIW, I don't think getting tests for phosphate, iron, and potassium are needed in most cases, particularly in a low tech tank.


Agreed, I've never tested for Potassium or Iron ever in my tank.


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## Asteroid (Jul 26, 2018)

Unless it's a store specifically setup for planted tanks or they have a very successful hi-tech planted section in the store you can assume the advise given is about a "fish tank" and not a "planted tank with fish in it"


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## LidijaPN (Jan 15, 2022)

Asteroid said:


> Unless it's a store specifically setup for planted tanks or they have a very successful hi-tech planted section in the store you can assume the advise given is about a "fish tank" and not a "planted tank with fish in it"


For sure.... So what y'all are sayin' is..... I ditch the phosguard?


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## Asteroid (Jul 26, 2018)

LidijaPN said:


> For sure.... So what y'all are sayin' is..... I ditch the phosguard?


I would. Most algae issues as discussed in numerous threads are the result of light/organic/co2 issues and no fertilizer amounts.


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## LidijaPN (Jan 15, 2022)

Asteroid said:


> I would. Most algae issues as discussed in numerous threads are the result of light/organic/co2 issues and no fertilizer amounts.


Drat, 17$ for nothing :/


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