3 replies to this topic

[FishGuyJosh]

I admittedly spend less focus on our lab's quarantine tanks than I should. I focus more of my water quality attention on my main holding systems, and they are running great. However the problem I run into is that when I get a sudden influx of new fish in our collection our quarantine system are in poor balance, and I have to spend a lot of time doing water changes to keep the fish healthy and infections down. To be perfectly honest that lack of attention has often made my life and the life of the fish harder.

 

In an effort to amend that, I have been trying to cycle my quarantine tanks with a few small bullheads. My plan is to keep them or other small fish in the tanks at all times so that I can already have nice cycled tanks ready to receive any new quarantine fish or sick fish from my main systems. Currently most of the tanks are doing well in the cycling process. All but one of the tanks actually has fish that need to be quarantined in them. The one that doesn't is holding a few bullhead. The issue I'm having with that particular tank keeps getting crazy pH drops overnight...like from 7.2 to 4.2. Is this simply a cycle crash? Is there any suggestions going forward?

 

The quarantien systems consist of the following...

(3) 20 gallon tanks, no substrate, each with a submersible UV, each with an Aquaclear 50 hanging filter

(2) 100 gallon tank, no substrate, each with two submersible UVs, each with two Aquaclear 70 hanging filters

 

One of the things I was gonna try was some crushed oyster shell in a filter bag to help buffer the pH. I've been adding baking soda to the tanks to keep them stable, but it's just not working for this particular tank. Any thoughts from my fellow NANFAns

[dac343]

Wow that is a pretty extreme drop especially for overnight. Do you only measure pH? Perhaps checking alkalinity and hardness would be a good idea too. Honestly such a large drop like that would have killed most fish. Does it come back up during the day? Or do you have to do water changes to bring it back up?

[gerald]

I'm guessing your conductivity is very low, probably less than 80 uS ??  If so, it takes very little change in ion concentrations to cause a huge pH swing. pH is determined by the ratio of proton-donor ions to proton-acceptor ions, and if the total amount of ions is really small, then a small change has a big effect on that ratio.  But the effect on fish may be not all that significant, because the water chemistry hasn't really changed very much.  Dac's comment "a large drop like that would have killed most fish" is true in water with more dissolved ions.  pH is just not a very meaningful measurement (for fish) in water with ultra-low ion content.   Yes I would use oyster shell or aragonite gravel to boost the alkalinity and hardness.

[strat guy]

It's a different situation than yours, but my tanks used to be black water south american tanks filtered through a lot of peat, and so keeping the pH stable was an issue. I used limestone rocks. Limestone constantly leeches minerals into the water and will be a good buffer to guard against pH drops. It's easy to find around me, so it was a good choice. Never once had an issue with pH drops at night and fish were always healthy.
On another note, and maybe someone can overrule me, but I would think scaleless catfish would not be good choices for quarantine tanks due to their susceptibility to skin and fungal infections? Not to mention that scaleless species are more sensitive to medication than other species in the case that you would need to treat the tank.