Beige colored goo

[jeffareid]

My fish tank has had this beige colored goo in the gravel, and under the gravel. It's just one fish in a 55 gallon tank, so I can't figure out what the source of "food" for the goo is.

Worse yet, the undergravel pumps (well submerged) started occasionally emitting bubbles, and when I looked underneath, there was a bit of very dark goo. Not knowing what type of gas was being generated, I cycled the entire tank (steps below).

What is the biege goo, and how do I control or eliminate it?

My wife decided years ago to stop getting new fish for the tank and then get rid of the tank when the last fish died. However, we now have a Clown Loach that's doing just fine at over 10 years old (she named him Lucky).

The tank is a 55 gallon show plastic tank. There are two AquaClear 50 undergravel pumps, an Eheim Ecco 2232 external cannister filter, a Neptune tube type water heater, and an air pump driving two air stones. There are plastic trays connected across the tank under the gravel to provide a path for the water to circulate downwards through the gravel and out the pumps.

This is the procedure I used to cycle the tank:

Syphoned water from the main tank to fill a 5 gallon tank.
Transferred the external filter, heater, and air stones to the 5 gallon tank.
Transferred the fish to the 5 gallon tank.
Drained the main tank.
Removed the gravel, and undertrays.
Disposed of the old gravel.
Cleaned out the tank and gravel undertrays.
Cleaned out the underwater pumps.
Re-installed the gravel undertrays.
Rinsed out new gravel (50 lbs), and installed it into main tank.
Filled the tank with new water, monitoring temperature.
Installed the underwater pumps and started them.
Added Amquel and NovAqua (6 teaspoons each).
Waited 45 minutes.
Removed external filter from 5 gallon tank.
Cleaned external filter, and installed new filter floss and ammo carb.
Rinsed out the ammo carb section.
Reinstalled external filter back to main tank.
Transferred heater and air stones back to main tank.
Verified heater cycled to confirm water temp was correct.
Transferred fish back to main tank.
Transferred 1/2 gallon of the old water to main tank.

[William]

are you siphoning the gravel regularly.

[jeffareid]

are you siphoning the gravel regularly.Yes, but the goo was coming back very fast and permeated the entire gravel bed. Before I upgraded the filter and pump, it was clogging them up. With the new higher flow external filter (Eheim Ecco 2232 - 400 liters - 105 gallons / hour) , and the very powerful undergravel pumps (AqualClear 50's - 757 liters - 200 gallons / hour each), nothing gets clogged.

I suspect that the new undergravel pumps sucked the goo right through the bottom of the gravel bed, as the goo accumulated under the gravel trays at the center of the tank.

At another forum, someone thought the goo might have been cyano bacteria, but I don't have any photos so I can't be sure.

[Lady Hobbs]

Is this brown algae or fish waste? Sounds to me as your UGF are not working properly or pumps didn't work sufficiently. If it was me, I'd get rid of the UGF totally and just do a good gravel cleaning now and then. To me, they're just a good area to trap nasty stuff.

[jeffareid]

Is this brown algae or fish waste? Just one fish, so it must be brown slime algae. It's all clean now, but I'll wait and see. With the newer, stronger pumps and external filter, nothing is getting clogged up, but I did see some slime on the input section and bio balls on the external filter.

[Lady Hobbs]

That's good is about gone. Hope these new filters work better for you. Does you tank get enough light? Sometimes you can get that brown stuff from being too dark too much.