I have 4 tanks that are getting this growth. I had it before but in different tanks. I have never seen it before and its starting up the glass. I have a tank up the road at work and there is nothing wrong with it. Same water same everything. This is only in 4 of 16 tanks. These have been cycled for over a year and get weekly water changes they are 10gallon tanks with a few guppies in one and some swordtails in one and black neons in one and one is empty. A couple have plants a couple have nothing they get the same light and I left the lights off and fed lightly for 2 weeks to see if it was an algea. I am lost. I dont want to tear these all down too and build up again like the ones 6 months ago. I got all new nets when I reset those tanks incase its cross contamination and each tank has it's own net. I am attaching puctures the only thing really hard to tell is that this stuff is sticky and the gravel comes out in chunks and I can't even scrub it off.
Any help is so much appreciated wince I am close to giving up on tanks here. I have never seen this in 24 years of fish keeping. Though the last six has been on city water when I moved the first several was on well water.
Note: The picture with the guppy in it was before shutting lights on the tanks the one where there is no fish and its darker is today after the lights have been off.