Discus tank odor problem solver

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soup
Posts: 11
Joined: Thu Feb 23, 2023 10:09 pm

Discus tank odor problem solver

Post by soup »

My tank's been smelling kinda funky lately, like rotten eggs. It's a 75-gallon with 6 Discus, all around 4 inches. I do 50% water changes twice a week, use a Fluval FX6, and feed them frozen beef heart and flakes. Tankmates are 10 neon tetras and a bristlenose pleco. Substrate is sand, and I've got some driftwood and Amazon swords. Any ideas what's up?
luxe
Posts: 10
Joined: Sun Jun 25, 2023 6:52 am

Re: Discus tank odor problem solver

Post by luxe »

Rotten egg smell usually means hydrogen sulfide buildup in the substrate. Sand can trap debris and create anaerobic pockets. Try stirring the sand gently during water changes and maybe cut back on the beef heart, it's messy. Also, check if your filter flow is strong enough to circulate the whole tank. What's your nitrate level?
Dream
Posts: 2
Joined: Sat Aug 03, 2024 9:37 pm

Re: Discus tank odor problem solver

Post by Dream »

luxe wrote: Mon May 12, 2025 5:54 pm Rotten egg smell usually means hydrogen sulfide buildup in the substrate. Sand can trap debris and create anaerobic pockets. Try stirring the sand gently during water changes and maybe cut back on the beef heart, it's messy. Also, check if your filter flow is strong enough to circulate the whole tank. What's your nitrate level?
Exactly this. I'd add a powerhead to increase flow if your FX6 isn't cutting it. Also, test for nitrates and ammonia just to rule out other issues. How old is your substrate?
soup
Posts: 11
Joined: Thu Feb 23, 2023 10:09 pm

Re: Discus tank odor problem solver

Post by soup »

Thanks, both! Substrate is about 8 months old. Nitrates are around 20 ppm, ammonia and nitrites are zero. I'll try stirring the sand and maybe grab a powerhead. Gonna skip beef heart for a bit too.
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BoldOne
Posts: 10
Joined: Tue Dec 27, 2022 2:26 pm

Re: Discus tank odor problem solver

Post by BoldOne »

Yo, that smell is sketchy. Had the same issue last year. Turned out my pleco was hoarding food under the driftwood. Check all the nooks, especially if you've got caves. Also, how often do you clean the FX6? Those sponges can get nasty.
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finch
Posts: 3
Joined: Thu Oct 10, 2024 3:03 am

Re: Discus tank odor problem solver

Post by finch »

Agree with checking the filter. I clean my canister every 3 months, but with beef heart, you might need to do it monthly. Also, consider adding more plants like hornwort—they help with water quality and might absorb some of the funk.
cadence
Posts: 2
Joined: Sat Apr 27, 2024 11:34 pm

Re: Discus tank odor problem solver

Post by cadence »

BoldOne wrote: Mon May 12, 2025 8:09 pm Yo, that smell is sketchy. Had the same issue last year. Turned out my pleco was hoarding food under the driftwood. Check all the nooks, especially if you've got caves. Also, how often do you clean the FX6? Those sponges can get nasty.
For real, plecos are sneaky like that. My buddy's tank reeked until he found a stash of pellets behind a rock. Maybe feed less for a few days and see if it helps.
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