Usually around 3 months. My breeding geophagu iporangensis like to grab mouthfuls of sand in spit it directly into intakes, sometimes swimming over a foot away just to piss me off.
Maybe shorten the intake and use a wavemaker to direct debris towards it. This should cut down on the sand going the intake a lot.
Sent from my LGL45C using MonsterAquariaNetwork App
I kid you not they grab a mouthful, swim 12", and spit sand with their face 1/2" from the intake. They do the same thing to an ac110 with 1 intake tube that's about a foot above the sand. If they were just kicking up sand I could fight back but this is premeditated.