To HOB or not to HOB

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Quest

I use the foams that come shipped with the Eheim units or coarse pre-filters like those used for pond systems or the ones that ship with Penguin reverse-flow power heads. Can use finer/denser foam but then one has to make sure that they get rinsed regularly (every 1-2 weeks) or they will generally clog and collapse. It only takes a couple minutes and is much preferable to breaking down the whole unit.

Regarding "waste", my theory is that bacteria never sleep and that most of what is available for vacuuming once every week or two is already spent in terms of what it can contribute to nitrogen chemistry.

As an aside, the faster the flow rate the less time the bacteria has to do it's work. The Eheim wet-dry units actually briefly hold the water between outflows and are reported to be around 70% more efficient at breaking down nitrites. As such I'm inclined to view flow rate as a relative rather than absolute measure of filtration efficiency, that is, a filter can move a lot of water but that doesn't imply that it purifies it as well or completely as something that has a lower flow-rate but provides a better/longer interface between the bacteria and water-borne waste.

Occurs to me that if processed waste was actually an issue that the matten/Poret filters that are cut to fit the whole width of a tank and that need only be cleaned once a year would be fatal to the fish since they get completely impregnated with sludge over time. Not saying the stuff is an asset or that "cleaner" isn't better, but I really think that it (brown stuff/particulates) is of little consequence or concern if filtration is otherwise adequate.

 

[mchambers]

I agree with Sam. I religiously clean my Eheim canisters . . . every six months. I clean the prefilters every month or so.

I prefer the coarsest Poret foam for prefilter material, but Sam's solutions work, too. I have a few ATI prefilters and like them.

I have 3 HOBs, all Aquaclear, but find that they require more maintenance than my canisters. They also are quite bit noisier.

 

[dogofwar]

I think the key is that all brown stuff on the bottom of a tank is not the same. I use dried leaves in some of my tanks. Those tanks tend to have more detritus in them than the tanks that I don't. Same with the tank with the Royal Plecos, which eat and poop massive amounts of wood.

The brown stuff in most of my tanks (and mixed with the leaves and wood), though, is poop (i.e. nitrogenous waste). And the bacteria in the tank/filters reduce it to nitrate.

Nitrates are a primary driver of the need to do water changes (and the amount that you need to change). Water changes dilute the amount of nitrate in the tank. While it's not possible to get to zero (if you have a functioning biological filter and most sources of water), lower is better for fish.

More and larger water changes are required to get to the same nitrate level for a tank with more waste in it than one that has less.

The more waste you can remove BEFORE it's "broken down" by nitifying bacteria, the easier it is to maintain low nitrate levels. That's the purpose of siphoning poop and uneaten food off of the bottom and "cleaning" mechanical filtration (e.g. cleaning pre-filters and cleaning filter fluff).

I think that the saving grace for most of us is that we do a lot of partial water changes and stock reasonably. Folks with live plants also have a built in source of nitrate reduction. Further, ammonia is much more toxic at higher pHs than at lower ones. And most cichlids and cats are pretty tough fish

That said, would you allow an HOB (with a pre-filter) go for 6 months without changing it? Or a box filter?

Most of my tanks have a box filter (with lots of air) and a sponge filter with less. I want the (frequently changed) box to catch the poop and uneaten food so that I can remove it. And I don't want the sponge to act primarily as a bio filter and NOT as a mechanical filter (which it will with high air).

Like using a canister with a pre-filter, this lowers but doesn't eliminate the amount of poop (or eventually broken-down previous poop) in the sponge filters...so I rinse them every couple of months (in tank water). I similarly siphon/rinse my Porets with water changes and remove and clean every couple of months (and I use the most course Poret).

Different approaches and this is what works for me. Someday I'll have a green-housey kind of set-up that will facilitate plants and I'll need to turn over a new leaf

Matt

 

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I hope some a y'all ar findin this edjicayshonil

I think the key is that all brown stuff on the bottom of a tank is not the same. I use dried leaves in some of my tanks. Those tanks tend to have more detritus in them than the tanks that I don't. Same with the tank with the Royal Plecos, which eat and poop massive amounts of wood.

The brown stuff in most of my tanks (and mixed with the leaves and wood), though, is poop (i.e. nitrogenous waste). And the bacteria in the tank/filters reduce it to nitrate.

Nitrates are a primary driver of the need to do water changes (and the amount that you need to change). Water changes dilute the amount of nitrate in the tank. While it's not possible to get to zero (if you have a functioning biological filter and most sources of water), lower is better for fish.

More and larger water changes are required to get to the same nitrate level for a tank with more waste in it than one that has less.

The more waste you can remove BEFORE it's "broken down" by nitifying bacteria, the easier it is to maintain low nitrate levels. That's the purpose of siphoning poop and uneaten food off of the bottom and "cleaning" mechanical filtration (e.g. cleaning pre-filters and cleaning filter fluff).

I think that the saving grace for most of us is that we do a lot of partial water changes and stock reasonably. Folks with live plants also have a built in source of nitrate reduction. Further, ammonia is much more toxic at higher pHs than at lower ones. And most cichlids and cats are pretty tough fish

That said, would you allow an HOB (with a pre-filter) go for 6 months without changing it? Or a box filter?

Most of my tanks have a box filter (with lots of air) and a sponge filter with less. I want the (frequently changed) box to catch the poop and uneaten food so that I can remove it. And I don't want the sponge to act primarily as a bio filter and NOT as a mechanical filter (which it will with high air).

Like using a canister with a pre-filter, this lowers but doesn't eliminate the amount of poop (or eventually broken-down previous poop) in the sponge filters...so I rinse them every couple of months (in tank water). I similarly siphon/rinse my Porets with water changes and remove and clean every couple of months (and I use the most course Poret).

Different approaches and this is what works for me. Someday I'll have a green-housey kind of set-up that will facilitate plants and I'll need to turn over a new leaf

Matt

Yeah yeah, I get it (note repeated previous emphases on need for water changes), and loathe seeing poop accumulating in little piles because of current in tanks as much as anyone, I just don't think it's that big of a deal but then I don't have giant log-munching plecos in my tanks either. I happily neglect HOBs for 6 months+ when I can (don't use box filters for aesthetic reasons though they are essentially just small internal canister filters), and do so regularly especially with larger ACs, not just because I can but because they all have pre-filters that get rinsed regularly and because the waste that accumulates inside them is the same as what piles up in my canisters, that is to say, spent, rendered, broken-down, irrelevant - any nitrites that entered have been converted, the resulting nitrates have dissolved into the tank water and at that point whatever remains in the filters is basically just dirt and effectively inert. So why should anyone care? It's a bit like the question of when and how often does one rake the leaves in the yard? Provided they're not blocking the door or so dense that they're creating run-off problems for rainfall (water flow), they're not hurting anything, and if I gather them all up and a few more fall does that mean I should run out and collect them as well? No. In fact if I ignore them completely they'll eventually disintegrate and disappear (dissolve), not unlike the waste entering a filter. Mostly all I'm saying is that undigested waste is/should only be an issue outside a filter, not inside, and that the use of pre-filters on canisters/HOBs not only increases biological filtering capacity but makes maintenance far simpler - so much so that other "maintenance" may not even be necessary save for every 6-12 months or more. For those who want and feel the need to break down those big honking Fluvals every week or two (or smaller HOBs), have at it, I'll stick with largely ignoring mine for extended periods in favor of rinsing pre-filters and spend my time elsewise. And anyway, I like accumulating brown stuff - it's great for houseplants (and scaring small children).