Jho's 75 Gallon

Since I posted a thread on my 55 gallon growout, I've decided to post one on my existing tank as well. I've had this group of 12 Na discus for about a month now, having bought them from Golden State back in Oct. In this group I have 4 varieties, 2x of albino red diamond, 2x albino pearl diamond, 2x albino golden crystal, 2x pigeon checkerboard, and 4x white pigeon checkerboard. The white pigeon checkerboard is a more obscure variety, since I was unable to find other suppliers who bred the same type. From it's markings, I believe it was a failed attempt to breed a snow leopard, as it has the same snow white coloration and red blotches. Photo below

With 12 almost fully grown discus, this tank should be considered overstocked. I've tried to up the w/c's to account for the increased density, but I feel the discus are still not thriving. I believe they're somewhat stressed as they display partial peppering and show darker fins, and one has been exhibiting active signs of hex. He has become pale in color, lethargic, slower to feed, and has been pooping stringy white feces. To remedy the problem, I've been dosing metro every day and performing regular w/c's. With people performing daily w/c's on a normally stocked tank of 6 discus, I think I'll have to do 2x daily. But it has been quite difficult to do so, as I need to attach a hose to the nearest faucet that's 50 ft away to do w/c's. In the future, I plan to move the tank to an outdoor shed w/ easy access to a faucet.

Following are photos of the fish:
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