It's green water. Nothing to be worried about, breeders actually love it because the fry will eat it and become healthy as can be with minimal loss.
Personally I would do more like 75-100g water changes weekly for your setup (23-30%). Your schedule is crazy. If anything do small WC's after feedings. Vac the poo, excess food and done. Thus reducing waste buildup and your nitrates. With your WC's your losing some beneficial bacteria believe it or not. Not enough to ever cause a spike, but some none the less. Everything that's in the tank below water will have some bacteria on it, substrate, glass walls, filters, everything. Doing those WC's is nearing the same way that people do WC's without a filter at all.
I didn't think my wc sch was to crazy I feed about 1 pound of food a day 6 days a week lately. With the sump full its about 315 gallons. Not to worried about losing BB Running 24 liters of matrix approximately 5 liters of ceramic and 6 gallons of bio balls. I do buy prime by the gallon though LOL.
I know its not long comparatively speaking but, In my 6 years of having tanks I have never saw a algae problem this bad. Looks like a toxic waste site. I'm getting impatient waiting on the UV.
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