Hi I bought a ph testing kit after a new addition to my tank died within a week. The ph is 6 which I believe is too low. The nitrite and ammonia is 0 and my two goldfish and 3 frogs are all fine. I would like to raise the ph before adding another fish. My source water (tap water ) is also ph 6 which explains the low ph in the tank. Also will raising the ph harm the existing fish as they are used to it at current level? Happy New Year Paul

Hi Paul,

Yes, pH of 6 is too low for comforts. The problem is that your source water is also 6 when means that everytime you change water, your pH is going to get a hammering. The safer way to sort this out is to increase your alkalinity or KH instead of some commerical ph+/- treatment. Do you have a KH & GH test kit? You will need one to do the necessary fine tuning. Unfortunately, you are right that a sudden change in pH will harm the fish so you do have to do this gradually.

In the short term you can use some baking soda but in the long term, you will need to use things like crushed shell, bits of coral to maintain the buffering.

How big is your tank?

Hi my tank is 30" x 15" x12" I don't understand what you mean by kh etc. It sounds as though the most practical solution would be to add a piece of coral? I was hoping I could add something to the water I put in at water changes.

KH is carbonate hardness, some call it alkalinity. If you have a decent amount of carbonate in your water (KH >100ppm), your pH is more stable because the carbonate provides the buffering against a dropping pH. When you kH is very low or 0, the pH will swing wildly as there is no buffering.

You can add something to the water to change it such as baking soda but you need to do it gradually and carefully or the pH can shoot up very quickly too. That is why you need the KH & GH test kit to provide the feedback you need. It is best not to increase the KH by more than 20ppm in one day. Some commercial products will do a quick fix on the pH but that's all it is. It will give you the right reading for a few days and then nature will take over and swing the pH again. It is a very expensive way to do it.

Sounds like you need a KH test.

Your tank holds about 23 gallons.
Using my baking soda calculator, 1/2 teaspoon of baking soda should raise your KH by 20ppm. If we knew your starting KH level, we could estimate how much that'd raise pH.

I'd recommend adding 1/2 teaspoon of baking soda. predissolve in tank water then pour slowly into a high flow area. After it's had time to disperse in the tank, check pH again. The goal is to raise pH by about .4 per day till you get it up in the mid 7s. At that point, it would be good to add crushed coral or crushed oyster shell to a high flow area. Those dissolve when pH gets below 7.5 and will increase both your KH (carbonate hardness) and your GH (general hardness).

Keep an eye on ammonia. your biofilter bacteria don't like low pH either.

Thanks, Betty.

Thanks for your helpful replies. I have bought a product called 'Proper PH 7.5' from Aquarium pharmaceuticals inc. It was very expensive and I'll use baking soda once this is used up. I am going to slowly introduce it over a few days. I will also get some coral once the ph gets to a correct level. Best regards Paul

I have another question. What weight of coral would I need to add to maintain the ph in my 20 gallon tank? regards Paul

Dunno. Depends on the bioload in the tank I'd bet. I have maybe a cup of crushed oyster shell in my 55 gallon tank.