So while this may not be a "water and parameters" discussion per se, it may provide insight into someone's questions someday. So I recently purchased a 12 L Mr. Aqua (Hooray!). I have been running an emmersed setup with it for about two and a half weeks in order to give my HC and Glosso a little jump start. After about a week and a half I started noticing weird thread like stuff growing in the little bit of water in the front (it had accumulated about 1/4 inch of water). I didn't think anything of it until I recently flooded the tank and realized that what I had was an outbreak of hair algae. Lame! What ever tho. I rarely use chemicals, but the last time I had really bad hair algae in another tank I used (don't lynch me) algaefix. It worked perfectly. Anyway, I went ahead and used it again and the hair algae is no more.
However, there is much more to this story than simple algae. The equipment I am using for this new 12L I moved from an established 20 acrylic. I have been waiting to sell off my tiger barbs which call the 20 home in order to transfer the filtration and heater over to the 12L. I finally got motivated to tear down the 20 and as I am doing it I realize that the fish shop is closed because it was the 4th of July. Ok, I say. I can quickly fill up the 12, connect it with the old filter and avoid a mini cycle. Right? Wrong!
The worst part about this was I was leaving the next day out of town for four days so the tiger barbs were going to have to make it on their own. I came home 4 days later with 2 of the 5 tiger barbs dead and Nitrite reading that was off the charts. I quickly opened up an old filter and switched out biomedia from an established tank and filled the other filter up which apparently did not prevent the cycle as I had hoped. I did a 50 percent water change and hoped for the best.
The next day (today) I am at work and my fiance calls me to tell me that the 12L filter is not working and the 3 tiger barbs are gasping at the surface. Within moments one has sunken to the ground and isn't moving. Apparently (I know now) my needle valve for this tank (if feeds from a triple needle valve output) gushed open and flooded the canister with so much CO2 that it lost its suction (I feed the CO2 into the filter intake). I am on the phone, trying to educate my fiance on how to fix the filter, but she can't get it. I tell her to just scoop up the fish and toss them in the QT tank below. Forget acclimation, this is an emergency!
SIGH....back home now and the three barbs are in the QT tank. Two have begun to swim around and the one who sunk to the bottom upside down has at least righted himself upright, but there is no telling just yet. I know barbs are hardy fish, but nitrite and CO2 double attack is all bad. Anyway, thanks for reading this if you have gotten this far. Just wanted to vent my frustrations at my own doing.
I realize the thing I should have done was move them to QT right when I got home and saw the Nitrites. I just figured with all the extra established bio media and the 50 percent water change, the crew could ride out the rest of the cycle. They may or may not have been able to, but blasting them with CO2 removed any opportunity at success.