# 0 KH, CO2 and BBA



## Bobbybills (Nov 30, 2015)

After reading what seems to be a few hundred posts on our site as well as others regarding CO2 and BBA, my head hurts and I am getting nowhere due to conflicting and contrary statements and information.

Some background. Tank has been up for over a year and I recently transitioned from an irregular and unregulated method of adding ferts and nutrients to a structured PPS-Pro method. It took a few major water changes to get the water parameters in line with what should be. I noticed the other day, for the first time, BBA algae on two pieces of Manzanita branches. I say this with confidence since I handled one piece repeatedly on 4/1 during the first 50% water change as I did a small amount of rescaping while the water was low and I would have noticed the BBA tufts.

After the 2nd 50% WC using RO and RO essentials, I noticed that the CO2 solenoid was cycling more that normal and the ph was driven down below the 6.5 set point after a short amount of time after CO2 was being injected. I believed that there was less CO2 being injected since the duration of injection was much shorter then before. This is supposedly consistent with BBA outbreaks due to lower CO2 amounts.

I figured that it must be due to alkalinity since RO essentials only adds GH and not KH, and since the tank was at 2KH before the water changes, must be lower. So I measured KH now to be zero.

I researched BBA and panic set in. Went to my LFS and bought both acid and alkaline buffer by Seachem and raised the KH to 4. This shot the TDS way above the threshold increase recommended by PPS pro. So I did a smaller water change to reduce the TDS using straight RO no additives. GH now sits at 3 and KH between 2 and 3, or as a fifth grader could figure out, 2.5.

This leads me to the essence of this issue. Several well informed and successful hobbyist claim that low or no KH is ok and should not be cause for alarm. BUT, how do you inject sufficient CO2 to keep the algae in check if adding just a small amount drives ph to lower levels.

I am guessing that the only way to maintain CO2 at sufficient levels and maintain low KH is to allow the ph to drop accordingly, perhaps to 6 or lower, by changing the set point on the ph controller.

Does this make sense given the sudden appearance of Captain Black Beard? Or is this an over reaction and not worth trying to compensate for?


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## Oso Polar (Apr 22, 2015)

Bobbybills said:


> I am guessing that the only way to maintain CO2 at sufficient levels and maintain low KH is to allow the ph to drop accordingly, perhaps to 6 or lower, by changing the set point on the ph controller.


Correct.


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## Bobbybills (Nov 30, 2015)

@Oso Polar

Is there a floor for the ph if I continue with water changes at 0 KH?


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## badbart (Jul 28, 2009)

Not sure how you can use a PH controller with zero KH. I tried and gave up I ended up reminerlizing the water to a low kh.


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## Bobbybills (Nov 30, 2015)

badbart said:


> Not sure how you can use a PH controller with zero KH. I tried and gave up I ended up reminerlizing the water to a low kh.


That is exactly the issue now. I never had to worry about low ph or low CO2 until the RO essential use in place of Equilibrium. So my question is without a controller, how low will the ph drop given the same 3 bps without some method of governance.


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## Diana (Jan 14, 2010)

Why do you want to keep the KH at 0? 

You do not need a blend of proprietary products to stabilize the KH. If you add baking soda or potassium bicarbonate you can stabilize the KH wherever you want it, but I would first aim for about 2-3 degrees and see how the CO2 controller deals with it. 

Anything you add to the water can raise the TDS. You simply start with that as your base point, then add ferts until the change in TDS levels from fertilizer tells you to do a water change.


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## Bobbybills (Nov 30, 2015)

Diana said:


> Why do you want to keep the KH at 0?


Hello Diana, nice to hear from you again. Always helpful you are.

My tank has held steady at 2-3 degrees both GH and KH for 14 months, ph between 6.5 and 6.6 for the entire time due to the controller and super fine needle valve. I use a RedSea injector that I had from a few years ago and it mixes fine at 3bps limit.

So the answer is that I do not "want" 0 KH, but if I continue down the path or remineralizing RO water with just Ca and Mg, that is what I will get. After just two 50% water changes, it fell that far.

Perhaps it is just coincidence that BBA just appeared right after this parameter change. Or, the lower KH reduced the amount of time that CO2 was being injected and this lead to the BBA.

Many seasoned users on this and other forums do fine with 0 KH, so my question was if that is so, then how does one compensate then since just a little CO2 drives down ph. The previous poster recommends leaving CO2 on all the time without the set point.

I read the CO2, KH PH table and have always been in the green with 6.5 ph and either 2 or 3 KH. But at zero KH, can one even make 20ppm CO2 based on table?

Confused Bobby.


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## houseofcards (Mar 21, 2009)

I might have missed this, but why are you using RO water? How heavily plant is your tank and what light are you using?


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## Edward (Apr 11, 2005)

Bobby,
These so called CO2 controllers do more harm than good unless used with hard water and high KH. They don’t regulate CO2, instead they are chasing after pH dependent on KH levels. When KH fluctuate then CO2 is a mess.

There is a reason why ADA uses bubble counters and not CO2 controllers. 

The pH buffers messed up your water parameters, bad idea. 

There is nothing wrong with zero KH. Adding baking soda will never make it consistent. If you want you can put a piece of coral in the RO and aquarium. It will slowly buffer acidity naturally. So do most substrates and rock decorations.


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## Bobbybills (Nov 30, 2015)

houseofcards said:


> I might have missed this, but why are you using RO water? How heavily plant is your tank and what light are you using?


My tap is city well water in the NJ Highlands, full of minerals like zinc, copper, iron. Took a TDS in PPM right before the water softener and it is 631 µs at 58F. 

DIY light fixture w/ 24 Cree XM-L2 at 2100ma = approx 156watts, mixed equally cool white and warm white highest bin available. Also a few mixed red, blue and warm for sunrise and sunset but these are driven at 1000ma and 750ma.

Bump: @Edward

Yes I fully understand that with just Ca and Mg added to water change, KH will eventually drop to zero and that the consensus is that this is "not an issue". I do admit that when I noticed the BBA, total panic set in and my basic instinct was to restore the KH to what it had been previously. LIke I said, I did a 15% WC with straight RO to knock it back down to 2.5 again even though GH got knocked down along with KH.

I was not prepared for letting go of the safety net of my controller, however. So you are suggesting to let ph drop to whatever level it naturally wants by allowing the CO2 to run constantly at 3 bps without any timer or other method of governance?

Leap of faith my friend. I may need some Scotch for this.


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## Edward (Apr 11, 2005)

Scotch is a great idea, … how are we going to fix the aquarium?

First is the CO2. I would remove the CO2 Controller and set up fixed bubble rate. These are usual CO2 bubble rates on ADA aquariums.

3.5 gallon or 13 L, 0.5 bps 
5 gallon or 20 L, 0.5 bps
8 gallon or 30 L, 1 bps
15 gallon or 65 L, 1 - 4 bps
40 gallon or 150 L, 3 - 4 bps 
45 gallon or 180 L, 3 bps
60 gallon or 245 L, 6 - 8 bps 
160 gallon or 650 L, 3 - 6 bps 
230 gallon or 900 L, 5 bps
375 gallon or 1500 L, 5 - 10 bps
400 gallon or 1600 L, 6 - 8 bps

There is a sump in the setup which does affect the overall CO2 levels. You may need to dose more CO2 to compensate for the loss. Maybe drop checker would help. What is good about low KH is that CO2 overdosing is unlikely. 

Next is CO2 timer. Some people use timers synchronized with lights and some don’t. It is up to you. I like to keep things simple. Set it and forget it.

Next are algae. Plants react negatively to water parameter changes. It doesn’t matter if from bad to good or vice versa. Algae will take advantage at first. Then, new growth will be healthy and algae resistant. 

Next is KH. Corals, some substrates and rocks react to acidity. Lower the pH more KH is released. Also, the amount of KH will show up as increase in TDS so maintaining levels is covered. 

Next are water parameters. How to get rid of the pH buffers? Water changes with RO Essential Minerals. 

Next, … Scotch


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## Bobbybills (Nov 30, 2015)

@Edward

Just came across this discussion between Edward and Plantbrain. 
CO2 levels at zero KH - Fertilizing - Aquatic Plant Central

Things have changed since then. But the concept of using tap with RO, which would add back many of the lost minerals for proper GH and KH, would just raise the starting benchmark for TDS monitoring. However, I would be including minerals that are harmful as well. RO would allow me to start with no minerals and be able to add back in a controlled method what was needed.

I like this approach but am still not sold on 0 KH. I think what I could do is use the controller as a failsafe and begin to lower the set point during each successive water change with just RO essentials until the CO2 seems to level or at least no longer drive the ph down below the setpoint, which it did before I added back the alkaline buffer.


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## Edward (Apr 11, 2005)

What is rain KH? How come rain storms don’t wipe out fish populations?


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## bsantucci (Sep 30, 2013)

My tank runs at zero KH without issue. My pH drops down to 5.3 or so with the co2 on during the day. Zero issues with livestock or algae. 

Ditch the controller like other have said. Keep a constant co2 stream going into the water and just slowly adjust your co2 to find the threshold of your fauna. That's the best and easiest way to do it.


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## Bobbybills (Nov 30, 2015)

*rhetorical question?*



Edward said:


> What is rain KH? How come rain storms don’t wipe out fish populations?


Not sure about rain water KH, but since you are asking I would assume 0 and that fish don't die when it rains, so relax about the kh, yes?

From your tone I assume that you do not like my suggested plan of action with regards to using the controller as a lower limit so that pH does not drop too low.

I was going to ask about the ADA bubble rates you posted. Why do smaller tanks need more than larger tanks, the relationship to size is up and down, or did I read the chart incorrectly?


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## houseofcards (Mar 21, 2009)

The smaller tanks could need more based on plant mass, light, growth rates, you get the idea. Edward probably took those from actual setups, but generally speaking the larger the tank the quicker the bubble rate.

Yeah, honestly I would ditch the controller a well. I never understood why you need that. I would recommend turning your co2 off at night if you have fish/shrimp, etc. 

I have very soft water in New York, My KH is around 1 and my PH is around 7 and I add co2 to most setups and it usually gets down to around 6. This is not an exact science. I don't really test parameters anymore. If you have algae your probably running too much light or your tank has too much organic waste for your setup. Co2 isn't an algaecide. It simply helps the plants grow faster and in turn they take up more nutrients/waste that is taking away from algae. All the consistent co2 in the world is not going to help with algae unless there is enough plant mass to utilize it. If your thin on plant mass use a shorter light duration, add carbon/purgien. Less feeding/less stock until you find the sweet spot. It's not really a sweet spot more like a sweet range.


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## Bobbybills (Nov 30, 2015)

@houseofcards

It is not that I have algae beyond what I can tolerate for snails, flag fish and ottos, it is just that I noticed right after wiping out the KH with two massive water changes that BBA appeared. Not much but enough to notice. Consensus for BBA is low CO2 at which point I connected the dots and realized that the CO2 was cutting off after a short duration and driving pH down to 6.3 even though the set point is 6.5. So that is why I asked how to keep CO2 levels at 30ppm when just a little knocks pH down without buffer.

I have 70 fish in this 90 gallon tank and for me, the plants are there to support the fish not the other way around, so I am playing it cautious regarding removing the safety net of the controller. Every plumbing system in the U.S. under pressure uses a relief valve to avoid over pressure. Every electrical system in the U.S. has circuit breakers to avoid over amperage. It only makes sense that the controller is there, not just for entertainment value, but to provide some measure of security against something unexpected.

The tank was doing fine but I noticed a few months ago that the plant growth slowed, pearling stopped and many leaves were dying. I am following the PPS method to get water column under control, but the same method of dosing macros and micros and minerals is the same for no low, or high KH water. The TDS benchmark from remineralized tap/RO with ferts just moves up and down accordingly, this I understand.

It is called buffer for a reason so I am just proceeding cautiously so that nothing drastic happens, that's all. I was planning to keep the bps the same since it had not been a problem until the lack of kh, but if I allow ph to drop as well things should stay equal. If I just allow the CO2 to run steady all day, I do not know where it will land. I reasoned that if I lowered the setpoint slowly the CO2 would run longer during peak demand and still be set and forget.

Here are a few shots from a few minutes ago and one can still see plenty of room for improvement which I am hoping the PPM dosing will help. So my question is, does KH hurt?

And I hardly have to use the algae scraper since starting the PPS.


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## bsantucci (Sep 30, 2013)

The problem with co2 controllers is that it's not a constant co2. You get on and off periods where there is not co2 in the water. So you're actually getting less co2 to be honest.

A good needle valve is all you need for your security. I had bba when I ran my apex controller as a co2 controller. Got rid of using that and no more bba. Like I said, too much on and off of the controller. I think you're getting too hung up on the pH swing from co2. It's not a real issue for fish. When fish have issues from co2 it's not from the ph drop, but from the co2. So leave co2 constant, start low, and slowly over the course of a month increase till you hit your threshold. Backoff a bit from that point to make sure the fish don't struggle and you're golden. Your tank will reach a point of equilibrium at each level of co2 you run where it won't drop ph anymore. It's not like the constant co2 will just keep bottoming out in the tank. The plants produce oxygen throughout the day.


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## Edward (Apr 11, 2005)

Bobbybills said:


> So my question is, does KH hurt?


 KH when not excessive does not hurt. Fluctuating KH does.

So, how to maintain low and consistent KH? Nobody knows unless daily monitoring, testing and correcting is involved. It is simply not worth it. 

In nature, soft water fish breed in minimal KH levels < 1 dKH, not 5 not 10. Often the actual pH is lower then what we can achieve with CO2 due to tannins and peat. Fish get even happier.

I don’t test for pH or KH, it is simply not needed. It is what it is. Acidity will balance it out naturally with coral, substrate and rocks. I run aquariums like this for a very long time and have sustainable fish generations. I don’t remember buying fish.


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## Bobbybills (Nov 30, 2015)

@Edward

Here is the chart you posted. Please see me comments. 

3.5 gallon or 13 L, 0.5 bps 
5 gallon or 20 L, 0.5 bps
8 gallon or 30 L, 1 bps
15 gallon or 65 L, 1 - 4 bps
40 gallon or 150 L, 3 - 4 bps 
45 gallon or 180 L, 3 bps
60 gallon or 245 L, 6 - 8 bps 
160 gallon or 650 L, 3 - 6 bps <--------why does 160 gal need less than 60 gal and how many for a 90 gal.
230 gallon or 900 L, 5 bps
375 gallon or 1500 L, 5 - 10 bps
400 gallon or 1600 L, 6 - 8 bps


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## Edward (Apr 11, 2005)

Bobby,
3.6 g per 10 gallon or 40L of baking soda will add 3dKH and can be added with RO Essential Minerals. Problem solved?

The CO2 chart was taken from real life ADA applications. Houseofcards explained it well in post #16. 
Most likely the rates were adjusted according to drop checker indications. The point was to demonstrate that beautiful aquariums don’t need crazy CO2 rates. It is not that critical. Simple set it and forget it will do.


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## happi (Dec 18, 2009)

if the KH is 0 then PH controller is useless, it is already useless anyway. you will get BBA when there is too much co2 in the water and as the PH falls, it will reduce the bacteria activity which will results in high organic and that will results in BBA.


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## Bobbybills (Nov 30, 2015)

houseofcards said:


> The smaller tanks could need more based on plant mass, light, growth rates, you get the idea. Edward probably took those from actual setups, but generally speaking the larger the tank the quicker the bubble rate.


Edward referred me to you regarding bubble count. I don't mean to be disrespectful but that chart makes no sense what-so-ever since larger tanks have both less or more than the smaller tanks in no discernible ratio. So 3-6 bps average should work.



bsantucci said:


> The problem with co2 controllers is that it's not a constant co2. You get on and off periods where there is not co2 in the water. So you're actually getting less co2 to be honest.
> 
> A good needle valve is all you need for your security.


You made the point that the constant on/off could be reducing the actual amount of CO2. This is what I believe began to happen so I am going to drop the set point slowly until I see that the ph is no longer dropping. According to what has been stated, there is a natural floor that is not harmful to fish and inverts and beneficial to plants. Having the controller there as insurance only prevents catastrophe.



happi said:


> if the KH is 0 then PH controller is useless, it is already useless anyway. you will get BBA when there is too much co2 in the water and as the PH falls, it will reduce the bacteria activity which will results in high organic and that will results in BBA.


Back to confused. Are you suggesting that allowing the CO2 to run without the controller with 0 KH is what leads to BBA???


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## happi (Dec 18, 2009)

Bobbybills said:


> Back to confused. Are you suggesting that allowing the CO2 to run without the controller with 0 KH is what leads to BBA???


no what am saying is that you really cannot measure the Co2 with PH controller if the KH is 0, far as i remember, i could be wrong though. if your PH controller cannot measure the correct level of co2 then either you might be adding too much or too little co2. but most likely too much co2, bba loves co2.


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## Bobbybills (Nov 30, 2015)

@happi

That BBA likes CO2 is very different from the research that I did which seemed to suggest the other way around. If you are correct, then I ought to just allow the controller to limit the CO2 injection like it has been doing since inception but with 0 KH, will doing so also hurt plants as they would not be getting the same amount of CO2. Or, are you in the camp of keeping KH at a minimum value?

That was my original impetus to post the question how do you maintain sufficient CO2 with low KH without driving down the ph and the answer seems to be that you cannot.

Now "super confused", which is slightly more confused than "back to confused"


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## Edward (Apr 11, 2005)

Bobbybills said:


> That was my original impetus to post the question how do you maintain sufficient CO2 with low KH without driving down the ph and the answer seems to be that you cannot.
> 
> Now "super confused", which is slightly more confused than "back to confused"


 Both, plants and algae benefit from CO2 injection. 

Dissolved CO2 is carbonic acid which will lower pH as low as allowed against buffering KH or when hits its lowest point of 3.65 pH.

I have suggested adding 3 dKH in post #21. Easy to do with water changes.


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## Bobbybills (Nov 30, 2015)

Edward said:


> I have suggested adding 3 dKH in post #21. Easy to do with water changes.


I did that and you yelled at me for adding the Seachem buffers to get back to 3. I just made 30 gallons of RO with just the RO essentials as you have recommended. I am going to take new readings to determine the benchmark TDS because I have added and then diluted so my current readings are meaningless at 300μS.

Edward, as evidenced by the 2004 post I referenced between you and plantbrain, opinions have changed over time as more experience is documented under controlled conditions. That's fine and is the sign of true expertise in that you have not been stuck in old beliefs once empirical data told you otherwise.

But my intitial inquisition has only been partially answered. Yes I can maintain optimal CO2 levels by allowing ph to drop to equilibrium which you have explained properly; or by using buffers to allow full injection of CO2 and keep ph at a higher level. Perhaps this is two sides of the same coin, but I want to do what makes the most sense because in the real world application of these methods, they should not yield the same results long term.

That having been said, I like the idea of not overdoing things which attracted me to the PPS method to begin with.

I have decided to continue with only RO essentials and will allow the ph to lower on it's own slowly over time. My CO2 reactor is a Red Sea 600 and cannot handle more than 3 or 4 bps anyhow so perhaps the lower ph may not be an issue. If the BBA spreads I will reverse course and increase the kh.

Once again, thank you so much for your time and guidance.


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## happi (Dec 18, 2009)

Bobbybills said:


> @happi
> 
> That BBA likes CO2 is very different from the research that I did which seemed to suggest the other way around. If you are correct, then I ought to just allow the controller to limit the CO2 injection like it has been doing since inception but with 0 KH, will doing so also hurt plants as they would not be getting the same amount of CO2. Or, are you in the camp of keeping KH at a minimum value?
> 
> ...


maybe this will help:

What exactly causes BBA? Part 2 - Bacterial imbalance | UK Aquatic Plant Society

Bump: what kind of substrate is that? looks like something that should raise your ph and Kh by looking at it.


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## houseofcards (Mar 21, 2009)

Bobbybills said:


> Edward referred me to you regarding bubble count. I don't mean to be disrespectful but that chart makes no sense what-so-ever since larger tanks have both less or more than the smaller tanks in no discernible ratio. So 3-6 bps average should work.


I wouldn't get hung up on the exact numbers. Overall the BPS is directly related to tank size, but there are different variables in the tank due to uptake, dissolution rate, tank shape etc. As Edward mentioned those rates are probably based on whatever was required to keep the drop checker where they wanted it. 

It's really pretty simple. If you look at some large ADA tanks that's the way they keep it. They have 4 and 5 foot tanks with one ceramic diffuser providing all the necessary co2. I actually like in- tank diffusers since it's another visual check on the co2 entering the aquarium. 

Look at these tanks from the ADA Gallery in Japan. One diffuser. 
https://www.flickr.com/photos/viktorlantos/11457740316/in/photostream/

There's nothing wrong with reactors, as long as your able to monitor co2 levels since you don't want to lose any fish.


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## Edward (Apr 11, 2005)

Bobbybills said:


> I did that and you yelled at me for adding the Seachem buffers to get back to 3.


 Yes, because Seachem buffers are unlikely made of the suggested baking soda.

Seachem Acid Buffer:
_Proprietary mixture of salts. The identity and weight of proprietary, non-hazardous, main ingredients are withheld as a trade secret._

Seachem Alkaline Buffer:
_Proprietary mixture of salts. The identity and weight of proprietary, non-hazardous, main ingredients are withheld as a trade secret._

It looked to me like you didn’t want to give up KH buffering so why not use baking soda.


> I just made 30 gallons of RO with just the RO essentials as you have recommended. I am going to take new readings to determine the benchmark TDS because I have added and then diluted so my current readings are meaningless at 300μS.


 Why not adjust it back to proper TDS reading with more minerals or more RO water?



> Edward, as evidenced by the 2004 post I referenced between you and plantbrain, opinions have changed over time as more experience is documented under controlled conditions. That's fine and is the sign of true expertise in that you have not been stuck in old beliefs once empirical data told you otherwise.


 Curious, what are you referring to in my twelve year old APC thread?



> But my intitial inquisition has only been partially answered. Yes I can maintain optimal CO2 levels by allowing ph to drop to equilibrium which you have explained properly; or by using buffers to allow full injection of CO2 and keep ph at a higher level. Perhaps this is two sides of the same coin, but I want to do what makes the most sense because in the real world application of these methods, they should not yield the same results long term.


 I thing it goes down to what makes one more comfortable. We have in this thread compared inert, unbuffered environment to buffered one in terms of pH KH relationship. That may be an extreme because the buffering rate of coral and TDS reading can be monitored easily. Additionally, coral adds not only KH but also plant nutrients like calcium, chlorides and trace elements. Coral will be actively dissolving more KH when needed.

Baking soda works as well, but adds only, KH, lots of Na sodium and high TDS readings. Also have to use a lot at once. 



> I have decided to continue with only RO essentials and will allow the ph to lower on it's own slowly over time. My CO2 reactor is a Red Sea 600 and cannot handle more than 3 or 4 bps anyhow so perhaps the lower ph may not be an issue.


 Cannot go wrong at a fixed CO2 bubble rate, *without* a Controller and with a bit of coral.



> If the BBA spreads I will reverse course and increase the kh.


 Of course you will see more algae. Every change to water parameters will make plants temporarily sick and algae will take advantage. Especially the cryptocorynes will melt and regrow back. When I do large changes then I cut cryptocorynes with scissors at the substrate and they come back healthy.



> Once again, thank you so much for your time and guidance.


 Pleasure.


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## Bobbybills (Nov 30, 2015)

@Edward

I was referring the the current tank reading at 300μS. The remineralized is ready to go with just RO essentials and is 194μS made as follows 33μS RO + 161μS Remineralized. Rechecked 10 drops of Macro in 1000ml and got 68μS for a benchmark of 262μS. So tank is 38μS over due.

I mentioned the 2004 post because I found it interesting that your knowledge has evolved as new data was presented which to me is a sign of rational intelligence, compared to those who stay stuck in a mindset or one way of doing something just because they think that changing their minds is an admission of ignorance when in fact it is just the opposite. Sort of like calling Sir Issac Newton's theory of gravity stupid after Einstein's theory of gravity became evident. So it was a compliment.

I digress. If the BBA is just a result of a rapid parameter change (50%) and not a long term problem due to low KH and therefore reduced CO2, no need to alter the plan and I will proceed as planned without the additional buffer.


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