How best to lift my pH so that it stays higher?

[David Middleton]

Following my disastrous ammonia spike of a few months back (which killed all my fish -most in excess of 5 years old) I have cycled my 200 litre tank and now Ammonia, Nitrites and Nitrates are all very good again. During the process I had read that the cycling would be speeded up the higher my pH was. I purchased some crushed coral and within a day or so pH was 7. I would like to retain it around that figure but it has returned to about 6.2 - despite coral still being in tank. Is there a long term solution that does not involve constant adding of chemicals etc? I think Edinburgh water is naturally about 6.8.

 

[Magnum Man]

maybe limestone slabs???

 

[seangee]

What fish do you keep or are you planning to keep? 6.8 is perfect for many tropical fish from South America or Asia. I try to keep my tanks lower than that. I am actually envious of your tap water.

 

[GaryE]

I'm with @seangee . Everything depends on what fish you want, but that water is like mine here, and it's wonderful stuff.

Ammonia is less toxic (the chemistry is easy to look up - check ammonia and ammonium) at a pH below 7. If you are into rainforest fish, with that water and regular 25-30% water changes, you can have a great set up again.

Once you start modifying pH, you quickly discover it moves with every water change, and it doesn't matter much. What is important is the mineral content of the water (hardness). pH just sort of follows it most of the time, but hardness determines what fish thrive. And playing with hardness is a lot of precise work.

 

[Colin_T]

What fish do you want to keep?

What are the tank dimensions (length x width x height)?

What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website (Water Analysis Report) or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

Depending on what the GH of your water is, will determine what fish you should keep.

Angelfish, discus, most tetras, most barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (GH below 150ppm) and a pH below 7.0.

Livebearers (guppies, platies, swordtails, mollies), rainbowfish and goldfish occur in medium hard water with a GH around 200-250ppm and a pH above 7.0.

If you have very hard water (GH above 300ppm) then look at African Rift Lake cichlids, or use distilled or reverse osmosis water to reduce the GH and keep fishes from softer water.

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Dead coral skeleton (crushed coral), limestone and shells are all made from calcium carbonate and this will help to buffer the pH of the water. Depending on the fish you want, you may not need to buffer the water or you might need to. If you do need to buffer it, then add a bit more dead coral, limestone or shells and monitor the pH over a couple of weeks. If it is still low, then add a bit more and monitor for a couple more weeks. Continue adding small amounts and monitoring over a couple of weeks.

The pH drop during the cycling process because the filter bacteria use carbonates in the water and carbonates buffer the pH. The more carbonates that get used the faster the pH drops and the lower the pH ends up.

I wouldn't worry too much about buffering the water during filter cycling and if the pH does drop, you can add some sodium bicarbonate (baking powder) or do a big water change to replace the used carbonates. Once the tank has finished cycling, then monitor and buffer the pH if needed.

 

[David Middleton]

Thanks to all who have responded. Your comments are well taken.