# Phosphate based or bicarbonate based pH buffer?...



## nattery (Oct 6, 2005)

Having researched a couple items on pH adjustment of tap water, I need some advice on the following - for a fish ONLY aquarium, to alter your pH is it recommended to use a phosphate based pH adjuster (API proper pH 6.5, Seachem Discus Buffer) or a bicarbonate based pH adjuster (Seachem Acid Buffer)? The concern with excess phosphate in planted aquariums relates to the possibility of undesirable algae growth - understood. I have read articles claiming that phosphate in high amounts has been used as an algacide - in higher concentrations it will actually bind trace elements that do lead to algae growth, ex. iron (research from API). In a fish only aquarium there is no concern over the water chemistry requirements for growing plants, so how will excess phosphate lead to unwanted algae growth if the claim from API is true?


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## assclown (Dec 12, 2005)

thats a good one for HARRY.......where are you man?
IMO.......i think you are trying to LOWER your PH?
if this correct, use driftwood to ballance out your ph,
to raise it, use crshed coral in a nylon bag


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## harrykaa (Jan 10, 2005)

Ok, about the buffers.

Acidic buffers (phosphates, sulphates, bisulphates, humic acids), which will keep the pH down, resist rise in pH.
Phosphate buffers (H2PO4, HPO4-, PO4-- ions) will stop pH from rising above 6.86. But these buffers are not recommended for aquarium use because of their ability to cause extra algae growth.
Seachem Acid Buffer is a bisulphate adjuster.

Basic buffers (bicarbonates, carbonates), which will keep the pH up, resist falling of pH.
Baking soda (NaHCO3) is commonly used chemical for this purpose.
So Seachem Alkaline Buffer is a bicarbonate adjuster (Sodium, Potassium and Magnesium bicarbonates).

Combination of buffers, which do not allow the pH go lower or higher, work both ways.
A common and good aquarium purpose buffer combination is sodium bicarbonate - carbonate and sodium bisulphate - sulphate mixture. You can adjust the pH with these from 5.0 to 8.4.

Algae - phosphates
In general the greatest problem in natural water system eutrophication is the overabundance of phosphates. These are responsible of the algae bloom and particularly Cyanophyta bloom (blue-green bacteria). On the other hand excess of silicates will cause the Diatom bloom.

It may very well be that real high concentration of PO4 can harm algae, but it will certainly also harm higher plants. I would not use this method. The true key in algae control is the right balance of nitrates and phosphates and of course lighting, which will enable a vigorous growth of higher plants.

Harry


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## nattery (Oct 6, 2005)

Thanks to harrykaa for taking your time to elaborate on my questions. Let me ask you for your opinion in summary:
For a FISH only set-up (no water chemistry concerns for growing plants), what would you recommend:
a.) Use a phosphate based pH buffer, if so, what product?
b.) Use a bicarbonate based pH buffer, if so, what product?
The end goal would be to achieve a stable pH of 6.8, whilst minimizing the potential for algae growth.
Thanks again for all your help!


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## Dr. Giggles (Oct 18, 2003)

nattery said:


> Thanks to harrykaa for taking your time to elaborate on my questions. Let me ask you for your opinion in summary:
> For a FISH only set-up (no water chemistry concerns for growing plants), what would you recommend:
> a.) Use a phosphate based pH buffer, if so, what product?
> b.) Use a bicarbonate based pH buffer, if so, what product?
> ...


First of all what are the params out of tap, specifically pH, kH, gH and for what kind of fish ?


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## harrykaa (Jan 10, 2005)

nattery said:


> For a FISH only set-up (no water chemistry concerns for growing plants), what would you recommend:
> a.) Use a phosphate based pH buffer, if so, what product?
> b.) Use a bicarbonate based pH buffer, if so, what product?
> The end goal would be to achieve a stable pH of 6.8, whilst minimizing the potential for algae growth.


Well first of all, if you really want to set the pH to 6.8, you are going to need some buffering. This is because water changes will have an impact on pH and KH.
Now, the more far away your tap water is from desired parameters and the more you do water changes, the more you need buffering (to maintain pH 6.8).

Because of unwanted function of hydrogen phosphates (H2PO4 and HPO4) as a nutrient and growth promotion for algae, choose other buffers.

There are two good buffers that do not interfere the nutrient balance in the aquarium, namely bicarbonates (NaHCO3) and bisulphates. These products dissolve easily too, CaCO3 does not.

Using bicarbonates alone will set the pH higher than 6.8, possiböy near pH 8.0 and using bisulphates alone will set the pH lower than 6.8, possibly near pH 5.0.

So use both at the same time as double buffer.
For example Seachem advices you to
dose 1 part acid buffer and 1.3 parts of alkaline buffer to obtain pH 6.5; or
dose 1 part of acid buffer and 2 parts of alkaline buffer to obtain pH 7.0.
The final result depends on the water chemistry of your tank and cannot be predicted, so test starting from something like above.

Harry


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## Morpheus (Feb 12, 2004)

I recommend Seachem buffers. I use them together at a ratio that gives a ph of 6.5 and they work fine. Stay away from phosphate buffers they cause brown algae blooms and that will make a mess of your tank.


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