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Been struggling with my 75-gallon tank's bioload lately. Got 6 adult Discus, a school of 12 Cardinals, and 6 Corydoras. Running a Fluval FX6, weekly 50% water changes, but nitrates creep up to 40ppm by day 5. Anyone got tips to keep it stable without upping water changes?

That's a heavy load for a 75. I'd cut feeding to once daily, skip a day weekly. Also, try adding more plants like Amazon swords or floaters. They'll help suck up nitrates. My tank's similar, and that combo keeps nitrates under 20ppm.

Agree with Dkade on plants. Also, check your filter media. If it's packed too tight, flow drops and nitrates spike. I run sponges plus Matrix in my FX6, spaced out. Nitrates stay below 30ppm with 8 Discus in a 90-gallon.

Tonito wrote: ↑Sun May 25, 2025 12:12 am Agree with Dkade on plants. Also, check your filter media. If it's packed too tight, flow drops and nitrates spike. I run sponges plus Matrix in my FX6, spaced out. Nitrates stay below 30ppm with 8 Discus in a 90-gallon.

Second this. Media arrangement is key. Also, consider adding Purigen to your filter. It's a game-changer for nitrate control.

How often do you clean the FX6? Gunk buildup can turn it into a nitrate factory. I deep-clean mine monthly, rinse media in tank water. Also, what's your feeding routine? Overfeeding's usually the culprit with nitrate spikes.

Thanks, all. Gonna try the plant boost and Purigen. Didn't realize media spacing mattered—my sponges are jammed tight. Will adjust and report back.

If nitrates are still sketchy after tweaks, test your tap water. Mine's got 10ppm straight from the faucet. Had to switch to RO mix to solve my nitrate woes.

metiteh wrote: ↑Sun May 25, 2025 4:50 am If nitrates are still sketchy after tweaks, test your tap water. Mine's got 10ppm straight from the faucet. Had to switch to RO mix to solve my nitrate woes.

Good call. Also, how old are your Discus? Juveniles poop way more than adults. My tank stabilized once mine hit 4 inches.

Yo, landfall, what's your substrate? Sand traps way more waste than bare bottom. I switched last year and nitrates dropped big time. Still got plants in pots though.

My tap's clean but nitrates still high. Gonna try them floaters like Dkade said. Heard water lettuce works good.