Have a recirculating system that has been up and running for about 7 years. Standard system with 15 30'diameter x 4' deep tanks. Center drains and 10 1x1x8" airstones in each tank. Regen blower and common sump for all tanks. We have a mechanical fiter as well as biofilters and a UV sterilizer. All water returns from the sump. No problems ever. Last week we found 5 of the tanks had fish that were not eating the pellet food, and floating near the surface and appeared darker in color. We thought it might be a parasite so took those tanks off the system and put them on our flow through well system. (600 ft depth)
Performed water tests on all tanks and everything seems normal. (Temp, Ph, DO, nitrite, nitro,total ammonia, hardness, and alkalinity)
For the past 4 days fish have gotten worse in the isolated tanks AND now our other tanks have fish exhibiting the same problem. Lab tests positive for gas bubble disease in tanks.
Trying to figure out why both parts of the system are showing gas bubble disease. Relatively new to problems with our system since this is the first major issue we've had.