Low pH in Goldfish tank

[Roz]

I Have a 150 litre tank as follows:
- 4 beautiful fantail goldfish about 5cm long.
- Eheim canister filter.
- Gravel substrate.
- Live plants.
- A couple of shells.

Pic attached...

The tank is still cycling (fish-in cycle due to urgent need for a larger tank).

The problem - I have a consistently low ph, which is not ideal for goldfish. It is 6.4.

I tried adding the two shells a few weeks ago, to no effect.

The tap water is at about 7.5 to 7.8.

I asked at a lfs today what to do about it. They suggested adding a powder, but I read somewhere that this increases the ph too quickly, and that is very bad for fishies.

I don't think I can add anything to the filter as the canister contains trays of particular things.

Is there anything else I can do?

 

[Delapool]

Hi, very [FONT=&quot]inquisitive fish! A ph of 6.4 is getting a little low for good bacteria as well - particularly if a downward trend. Baking soda is a short term fix (not sure of impact on plants, I thought it was negative but just reading positive reviews) and crushed shells/coral will help longer term. Crushing to finer particles should speed up the reaction and a bag is hang in front of water flow in the tank.

However, as your water is quite good for the ph, I would just gradually increase the pwc's. I can't think of any harm there. Mostly I have seen it suggested not to go above a ph increase of 0.2 to 0.5 (more in the 0.2 to 0.3 range) in 24hrs. Do you know the kh of the tap water? Perhaps it is low. [/FONT]

 

[molliwopp]

Im wondering how the tank is at 6.4 when your tap is 7.8. I would agree that you should increase your water change routine gradually.

Id also agree that you kh could be on the low side.

 

[pip walters]

Your tap water is the ideal pH for nitrifying bacteria, so the BB will be mutiplying at their highest possible rate for the temperature available. As they multiply and convert nitrogen, they consume carbonates and bicarbonates, thus removing the buffering agents from the water and produce (if I remember correctly) carbonic acid, which further acidifies the water.

As other posters advise, regular water changes will help, but you may also need to add buffers. rushed coral, shells etc should help and you may also need to add bicarbonate of soda.

At the fish farm where I worked, I used to add bicarb daily via a clockwork belt feeder, which added a little at a time over a twelve hour period.

 

[Roz]

Thanks everyone.

I religiously Change 15% water every day to every 2nd day. Should I be doing more than that?

R

 

[Delapool]

Thanks everyone.

I religiously Change 15% water every day to every 2nd day. Should I be doing more than that?

R

I would increase this gradually and always a daily pwc at least until tank water is more similar in ph to tap water.

 

[Rivercats]

I've kept large (8+ inch) fancy goldfish for years and with the copious amounts of waste they can produce buffers in the tank water are quickly used. It's not uncommon for GF keepers to do 2- 50% WC's weekly. I did that for each tank but also used crushed coral in the filters.

 

[Roz]

Thank you everyone for your fantastic help and advice! I have increased the water changes and will monitor the pH.