Tested Low PH This Morning . Do I Need To Panic

Hi Alison 


Don't panic, as long as the fish are OK 

Very soft water often goes with low pH, and water companies sometimes add something to the mains water to increase pH so that an acidic pH doesn't corrode their pipework. These added things will gas out so the first thing to do is leave a glass of water to stand for 24 hours then test it. You may well find the pH is lower than freshly run tap water, and potentially could explain the tank's pH being lower than tap water.

Soft water usually goes hand in hand with low KH, carbonate hardness. Carbonate buffers the water against changes in pH. The natural tendency of a tank is to become gradually more acidic. Carbonate reacts with these acids to stop the pH changing. But where there is not much KH it get used up, and when there is none left the pH can drop. I have low KH (3 dH) and many years ago I was very lazy about water changes - and like you I did not test the pH regularly then one day discovered it had dropped off the bottom of the scale.
The way I solved it was by doing weekly water changes instead of when I could be bothered  and this tops up my KH enough to stop the pH dropping. I now do weekly 50% water changes.
You don't have many fish at the moment so less than weekly water changes shouldn't cause a problem by themselves, though this could be a cause with more fish.

Bogwood leaches tannins, which are acidic. This could be enough to use up all the KH if that is very low.


The only problem is that the filter bacteria don't multiply as fast as with higher pH. So if you are doing a fish-in cycle (I get that impression because you are adding fish slowly) it could take some time for the bacteria to keep up with an increasing fish load. At pH below 7.0, almost all ammonia is in the less toxic form ammonium, so if any does show up the fish should be safe. But there is no safe form of nitrite so if that shows up you'll need to do water changes.
However, if you were to use live plants, particularly floating plants, they will process ammonia faster than the bacteria, and they don't turn it into nitrite. Live plants will help keep your fish safe  You would need to choose plants that like soft acidic water, and other members will be able to help with this better than me.


Don't use a product for increasing pH. These chemicals cause more problems than they solve. I would just live with your low pH - there are lots of fish that are quite happy in very soft water with low pH. yes there are safe things you could add that will make the tank water slightly harder, and will increase carbonate and pH as well. But if you go down this route you will have to do it forever. And it will work out expensive over the years.




Personally, I would make sure I did 50% weekly water changes, have lots of live plants - and honey gouramis will like living in floating plants - and choose fish that like soft acidic water. And don't worry about the pH.

Hi Alison and welcome to the forum. 

I don't have any experience with soft water, or low pH, as I have the complete opposite. I agree with what Sue has said about taking a sample of tap water and leaving it to stand before testing. I had concerns about high pH not long after I started, I did what Sue is suggesting here, and I found that my tap water had a pH of 7.0 when fresh, and 8.2 - 8.4 after being left to stand for a few days (water is 17dH). I thought that there was something wrong with my tank that was causing the change, and it was quite a relief to find that it was the tap water.

I'm under the impression that a build up of CO2 could cause a lower pH. As long as your filter is causing some water movement at the surface to assist gas exchange, then it shouldn't be an issue.

Thanks for the advice feel quite chilled now and glad I have more plants on the way and will be researching tankmates that my Gourami's will get on with . Have seen on u tube that if you put half of a polystyrene cup to float in the tank the Gourami's  may build a bubble nest in that . Maybe worth a try .As you say Sue I researched the Cherry Barbs and they are very chilled and peaceful fish if a bit active in the baby making department my java moss looks like cotton wool at the moment they have spawned all over it . They did like my bogwood as well but think I will leave that out for now