PH different between tanks?

[liulady]

So, I was really surprised by something today and I wondered if any of you experienced folks may have the answer.

Ok, so we have 2 tanks going right now. A 10 gallon with one little goldfish and a 30 gallon that currently has 8 harlequin rasboras and 1 dwarf gourami. Both are completely cycled and the water parameters are perfect (0 ammonia, 0 nitrites, and 5-10 nitrates).

From the beginning, I've had rather high PH test results on the 30 gallon tank. It tends to hang out right about 7.8, but sometimes edges up to nearly 8 ppm. I don't usually even test the goldfish 10 gallon as that tank has been established for a long time and I just don't worry about it much. I tested it today, though, and was shocked to see that the PH level was around 6.6-6.8.

Wow! What would cause the difference between the 2 tanks? The water straight out of our tap runs about 7.4-7.8, so pretty close to what the 30 gallon tests.

Neither tank has real plants. Thoughts?

 

[Clownfishlover]

Maybe the different food affects the pH? Idk do you have natural drift work with your goldfish?

 

[Rivercats]

Goldfish produce a lot of ammonia and water tends to get acidic. As the buffers (calcium/Kh) get used up the ph drops. Sometimes just doing weekly WC's doesn't add enough buffers back into the water. If you do a couple large WC's and ph is still low you might want to consider adding crushed coral in a media bag placed in the filter or hung under the filter outflow. You will have to monitor Kh/Ph to see if you need to add or lessen the amount of CC you start with. It's a 10g tank so it shouldn't need a ton to start.

Now about goldfish and a 10g tank. How many and what type of goldfish do you have? Goldfish need a much larger tank than that. GF may start out small but grow quite quickly.

 

[liulady]

Thanks, Rivercats. That makes a lot of sense. I was actually thinking that I wish I could get the 30 gallon to drop like that...I'm not trying to raise it. Our tap water is high enough already and it is super easy to do big wcs on such a small tank.

I know the "drill" on goldfish. We were casualties of the usual big box petstore not telling us that 3 goldfish are too much for a 10 gallon...uncycled at that! So, this one is the lone survivor and he gets the tank to himself. When/if he outgrows it...we will deal with that at that time.

Thanks again for your insight on the PH issue. I was really curious as to what would have caused the drop.