Currently running two HOB filters on my 75-gallon but I'm seeing detritus piling up around the plants and the water quality tests are slipping. Someone at the fish store mentioned canisters are way more efficient. Is the upgrade worth it, or am I just overthinking this?
The detritus buildup and slipping water quality suggest your current setup isn't cutting it, so a canister would probably help - but before you jump on it, what are your actual test results showing, and are you doing water changes regularly? Sometimes the issue is maintenance habits rather than filter type, though canisters do offer better flow and mechanical filtration if your HOBs are genuinely undersized for a 75-gallon.
The fish store angle is worth considering but not gospel - they sell canisters for a reason. That said, your gut feeling about the setup struggling is probably right. Two HOB filters on 75 gallons should theoretically handle it, but HOBs have a real weakness: they mostly push water through the media without actually pulling debris off the substrate the way a canister intake does. Detritus sitting around plants is a red flag that your flow isn't reaching the floor where it matters.
Before committing money though, check what your actual numbers look like. If nitrates are creeping up, phosphates are high, or ammonia's not zero, then yeah - you need better filtration or flow. A canister would solve this because the intake sits on the bottom and you can position it to directly sweep debris toward the filter. But you could also try adding powerheads or repositioning your current HOBs first, which costs way less. And honestly, some detritus under plants isn't automatically bad if your water parameters stay stable - plants actually use that stuff.
What are your test results actually showing? That matters more than the visual pile.
Detritus piling up is a pretty clear sign you need better mechanical filtration - canister filters excel at this because they pull water through fine media way more aggressively than HOBs can. Before spending the money though, check if your HOB intake tubes are positioned right (they should be near the substrate where most detritus settles) and make sure the filter media isn't clogged - sometimes people think they need new gear when they just need to clean what they have more often.
What are you feeding and how often - could be overfeeding rather than a filter problem? That said, canisters do pull detritus way more effectively than HOBs since the intake sits lower and they have better flow through the substrate, so if your tests are actually dropping (not just visually messy), upgrading makes sense. Just make sure you're not just adding filtration to cover up a feeding or maintenance issue, because a canister won't fix that.
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