Tell your buddy to change the water those tanks look like they need some love. And maybe a stand.
He raises thousands of gold fish just for the grow water. He is a professional custom tank mfg and fish doctor. We made the bathroom aquarium for Magic Johnson of the Lakers. Walls and ceiling were tank glass. He knows what he is doing but just could give a shit about these gold fish tanks. He is probably thinking the nastier the better. Can't argue with the lazy grow method even if he is wasting light. He was a commercial grower with buryied shipping container grow till a local dispensary moved in and law stated that you can't have a grow within 3 miles? of a dispensary. EVen though he was there first. F'd Up AZ law. Now he is perfecting the Lazy Grow method for personal. He said he could get a pound out of 4 plants/light and tons of work or he could get a pound out of one plant/light and little to no work. Big pots from the start, little to no defoliating, one light/plant and water with fish water. I was supposed to try that grow this time till the wife over bought. Next time.
He probably has over 3000 gals of tanks for medicinal fish water and services many restaurants and celebraties tanks. He was the first importer of African Ciclids way back in the day but is no longer breading them. He is really busy and needs some Lazy days in the grow.