Updated 2/4/16, 2/22/16, 3/6/16
My 5-gallon Fluval-Chi is the tank that refuses to die.
After giving up the year-long battle against salt constantly crusting on the top outer edges of the tank, I moved the colony into the 18-gallon, with plans to decommission the Fluval-Chi. However, I was unable to net some tiny juveniles that hid in the gaps in the gravel substrate. I decided to keep the tank running, with no coral condo or lava rocks, until they grew large enough for me to net. The tank is bare, except for the substrate and UGF.
I had lowered the volume of water in the tank by about 50%, but salt crusting was still a constant problem. (The water level in the photo above is higher because I added water after the modification.)
I decided to alter the Fluval-Chi’s UGF. I’ve noticed that the 1-gallon and 1.5-gallon tanks with UGFs don’t have the crusting problem. The difference is they don’t have airstones in the exhaust tube. The smaller system is a lot simpler, with a nib next to the bottom of the exhaust tube. I simply attach an air line to the nib and the air forces filtered water up the exhaust and back into the tank. The large bubbles from the exhaust don’t seem to produce the kind of moist airborne bubbles that airstones do. This seems to keep salt from escaping out of the tank.
I decided to remove the airstone from the Fluval-Chi. Without the airstone, the pump didn’t provide enough bubbles to raise water out of the exhaust. I switched to a shorter exhaust tube and that did the trick. (In the photos, it’s the yellowed section. This is an older tube, yellowed by age.) Now, instead of foamy water bubbles streaming from the exhaust, I have water flowing out almost like a faucet.
It’s too soon to tell if this removal of the air stone from the UGF will solve the salt crusting problem, but I’m guessing that it will. If crusting is no longer a problem, then I may decide to fully revive the Fluval-Chi by gradually adding elements such as a coral condo and a lava rock or two. I may also raise the volume of water in the tank to bring it closer to the top.
I’ve now counted four tiny survivors in the Fluval-Chi. There may be a fifth. I’ll know for sure exactly how many there are as they grow bigger. I’m leaning toward keeping them as the sole inhabitants and hope that they can grow and multiply and, eventually, create a thriving colony.
A possible problem may be in-breeding. I’m not sure if this poses a threat to opae’ula regeneration. If this is the case, then I may need to introduce one or two opae from the 10- and 18-gallon.
This is a situation that I couldn’t have anticipated. Fascinating ongoing turn of events.
3/6/16 update: After a little over a month, I can tentatively report that this UGF fix is working. No salt crusting problem. Yet. In the past, salt started accumulating on the edges as early as a day after cleaning. Thus, a month is very promising. Still, I’ll continue to monitor this fix. I tried this same fix (removing the air stones) on the counter-top 10-gallon, but success has been so-so. Salt is still crusting, but it seems to be doing so at a much slower rate. The buffer between the surface of the water and the edge is only about an inch, so this might explain the discrepancy.