PH fluctuation and a lot of other info

[DaveP]

Hi everyone,

I've been browsing the forum for a few months and have learned a lot. One thing I do know is to provide specifics of your tank when you ask a question, so here goes.

58 gal.
Fluval 404 filter
5 discus total (2 discus that spawn on a weekly basis so I divided the tank)

I recently medicated for tapeworms because one discus was eating well but remained skinny. The medication definitely affected my denitrification bacteria because all the fish are stressed but still eating. (I should have used a Qtine tank)

I did a 50% water change yesterday (after the second day of medication) and the fish look better and are eating. I think they still have a long way to go.

PH- 7.3 - 7.6
KH - ~8
Daily water changes ~5-10%

Before medicating I was slowly lowering the PH and KH to try to get the eggs to hatch. I am now continuing to do this but I am noticing a flucutuation in PH of ~ .3. Usually 7.3 at night and 7.65 during the day. Is this too much of a fluctuation?
I beleive my canister filter is causing this since there is probably a significant amount of CO2 in the water at night (no light at night so algae can not utilize CO2).
Your thoughts would be greatly appreciated.

[FishLover]

Hmmm... .35 of a swing is bit too much IMO. Mine changes less than .15 from night to day. I measure mine few times a day because I was trying to bring the PH down too.

I do find out if I run the air pump all night, it will drive up the PH level a bit, .02 or so. Right now, I stopped running any air pump. No point of having it since my fish are not gasping for air at all.

Some medications will drive up the PH level. Especially for the fizz tabs. Every time I used them, it drive my PH up at least .5 or so and I it takes me up to 10 days to lower it down with WCs.

[DaveP]

I had these PH swings before I medicated. Maybe I should swap out the canister for a wetdry?

[Merrilyn]

Hello DaveP and welcome to the forum.

Good to see you are doing careful testing of your tank water. That's the way to keep healthy discus.

Now, with regard to worming medication affecting your bio filter, most of the recognised brands state that it doesn't harm your bio filter. Have a read of the packet, and tell me the main ingredient in these tablets. If it's praziquantal, then it doesn't harm your bio filter, but it may be mixed with another ingredient.

If your bio filter is affected, it will show up as a reading when you test for ammonia and nitrite. A fully cycled tank should have no ammonia reading at all.

Any level of ammonia will distress your fish, and you may need to take some used filter medium from another cycled tank, to reseed your bio filter. In the meantime, do daily water changes to deal with the ammonia problem.

HTH