New Member
Oct 26, 2018
I'm not sure what kind of algae this is, or if it even is algae.

It's a low tech set up with no CO2. Medium intensity 6500k (ish) LED floodlight. Unknown PAR. 2400 lumens.

55 gallons. Stocked low with three Guanacara and fry. They're spawning in this tank and water quality is decent with no ammonia, etc.

I've been doing PPS-PRO (it's the easiest for me to keep track of bc of memory issues), but didn't add it for two nights. This was following a 1/3 of the tank water change and filter foam rinsing. Aquaclear 70.

It seemed to appear overnight and it's damaging the plants where it touches them, as you can see in the pic.

I've since been doing the ferts again every night but haven't been able to shake this stuff.

I've also cut off the lights for a few days and also has made no difference.

It's reappearing as fast as I rub it off.

The test kits I have are: API Master, KH and GH, and a TDS/EC meter.

I'm having very high pH swings at night in my well water, so don't know if it's at all related.