To HOB or not to HOB

[Jefft]

Since entering this wonderful obsession we all share I have always leaned towards HOB filters preferring the AC models. I have noticed the larger gallon units many of you have and those available on CL or other markets for used tanks feature "sump unit filtration" set ups. I would love to know advantages/disadvantages of HOB vs. "sump filters"? My fears so far have been;
1.) structural integrity of a drilled tank
2.) Increased risk of undetected leaks in the down pipes thus flooding my neighbors downstairs. Leaky seals.. leaks in general.
3.) increased upkeep

Currently, I am in a 4th floor apartment so a 125 gallon is going to be about the biggest unit I can place, without "dropping in on the neighbors". Finding a unit that size or larger which has not been drilled for sump filtration is next to impossible without going new. So I would love a little discussion, pointers, debate whatever you can offer in the way of knowledge/experience offered.

 

[mscichlid]

Canisters are an option to consider.

 

[Reel Addiction]

You can plug off holes and stick with HOB if you want. Just because its a drilled tank doesnt mean you need to use a sump.

 

[Jefft]

So what offers the best filtration of water for the fish HOB, Canister, or sump?

 

[gravel_digger]

as with lot of things where there are options i think it boils down to personal choice and what you are comfortable with. i run HoB and canisters on all my tanks just because of the type of fish i keep.

 

[jonclark96]

Typically, most folks would agree that sumps will offer the most capacity from a biological fitration perspective. The down side to sumps is that they are typically noisier than other types of filtration, and if you do not have a drilled tank, there is always the chance of an overflow situation if you lose your siphon draining the tank. HOB's and cannisters don't have a big capacity and require more maintenance, but are almost silent if set up correctly. It's really up to you.

I think there is a breaking point when a tank is just too big to be adequately filtered without a sump. Probably once you get to around 300 gallons or so.

 

[dogofwar]

I find canisters to be unacceptably labor intensive to maintain - as they combine mechanical and biological filtration in one closed compartment, changing the mechanical media (fluff) - which should be done frequently - is a PITA... Pre-filters help but that also slows down flow rates.

HOBs are easier to clean and move a lot of water, but tend to have less capacity. Simply keeping Poret or another easily clean-able media in them makes life much easier and less expensive than buying pads.

Sumps are best in terms of biological capacity and ease of maintenance in my opinion. Installing one on a drilled tank isn't rocket science (plenty of folks could help you out with a DIY one) and I haven't heard about significantly more tank failures on drilled tanks vs. others.

That said (and this is the approach that I use, since my large tanks aren't drilled) is a hybrid of HOB and sump called a "dump" filter. It's basically a sump on top of your tank...with water pumped to it...and allowed to flow back to the tank via gravity. It's basically all of the advantages of the sump with greater efficiency (less pump flow lost to head and greater water agitation). I make mine out of clear rubbermaid containers but you can make them out of attractive plastic containers (planters, etc.) or place a rubbermaid into a nice ceramic one. The main disadvantage is noise. Water is dumping back into the tank, so (unless you build return tubes from the bottom of the filter into the water) there will be the sounds of water trickling back to the tank.

Almost all of the tanks in my fishroom are filtered with air-driven box filters and sponge filters. I have dumps on my larger tanks. Lots of ways to skin a cat (and filter a tank)!

Matt

 

[Tony]

I find canisters to be unacceptably labor intensive to maintain - as they combine mechanical and biological filtration in one closed compartment, changing the mechanical media (fluff) - which should be done frequently - is a PITA... Pre-filters help but that also slows down flow rates.

HOBs are easier to clean and move a lot of water, but tend to have less capacity. Simply keeping Poret or another easily clean-able media in them makes life much easier and less expensive than buying pads.

Yes and yes. Haven't owned an FX5, so I can't speak for how much better the average canister is in terms of ease of cleaning, loss of flow, etc. But most are IMO, a PITA.

I have four 6' tanks and all of them are filtered differently, depending on their stocking/bioload and location.

• 180 drilled (Adult large Malawi haps - Very high bioload) - sump with 1200 GPH return, AC 110 to pull solids out of the water column.
• 150 non-drilled (Medium-sized SA eartheaters - high bioload) - 2 Rena XP3 canisters, 2 AC110s.
• 125 non-drilled (Growout to small adult Malawi haps - Med bioload) - 2" Poret foam divider with 400 GPH powerhead pulling water through, 6 sponge filters, AC110
• 125 non-drilled (Tang featherfins/Cyps - Light bioload) - Poret foam bent into the corners (picture overflows in a drilled tank) with powerheads inside blowing water out into the tank, AC110.

So depending on what you're stocking - and how quiet/pretty you want the tank to be, you can get away with all different methods. All the tanks above have one or more large blowers in the tank to circulate water. They also get 75% weekly water changes, so adjust your filtration depending on the frequency of your changes.


If you have the room (and a drilled tank), go with a sump IMO. However, I will never set up another sump on a non-drilled tank. The over-the-rim weirs are just too unreliable.

 

[MonteSS]

I would run a canister and then a HOB to polish the water

...Bill

 

[Avatar]

In praise of pre-filters

So much depends on location, tank size, stocking, etc.

I love canisters, the older Eheims anyway (2026/2028/2227/2229), cannot/will not vouch for anything else, but the chances of me installing a sump filter let alone a dump filter on a tank situated in my bedroom or living room are nil. The Eheims are very quiet, simple, reliable and efficient and I don't even open them up more often than every 6 months (and I do use "fluff"), this using pre-filters which IME do not diminish flow rate unless/until they get clogged which never really happens if they're cleaned during weekly or every other week water changes. As for cleaning, with an Eheim you simply disconnect the double-tap unit from the pump-head (water stays in the lines), move the unit to the bathtub and five minutes later you're back in business. If you can manage anything close to that with a sump I'll be astonished. That being said, sump/dump units because of their size have more capacity and hence more potential than other filtration options. If someone was clever they'd design one (long and shallow/narrow) that fits on the top/back of a tank so that it could double as a hydroponic unit while eliminating the risk of leaks and need for drilling - you could run it with a mere powerhead and put drain plugs in it for periodically purging accumulated waste. I've seen homemade jobs that used inverted light hoods and just air to create flow for such that basically resembled miniature wetlands but better would be a long semi-open-top AquaClear type unit.

For anything 60 gallons or less am not sure there's a better option than AquaClears at present unless you're talking much smaller tanks that can use sponge filtration. More filtration is always better but if your system is adequately breaking down waste at a certain point excess filtration becomes just that - might do the job faster but it can't process what doesn't exist.

I'll bet that there are a bunch of people in CCA using AquaClears exclusively on large tanks without ill effects. Fact is almost anything will work- including unattractive jerry-rigged tupperware bins filled with plastic army men precariously perched atop tanks - but none of it can replace regular water changes, not overstocking, overfeeding, etc. If you do go HOB, just don't buy anything that uses replaceable cartridges - hands down the biggest con job in the trade at present. And if that's what you already have, fine, just rinse and do not replace the cartridges. Meaningful filtration is almost 100% about bacterial colonies and maximizing surface area to enable same - new cartridges are sterile almost useless things and are just beginning to perform well at the point that most manufacturers are telling you it's time to replace them.

PS- All canisters are not created equal anymore than HOBs. I bought Eheims (all used and all on Ebay/CraigsList) because they were the only canisters that folks seemed to consistently swear by rather than at, and because they're German-engineered and aesthetically pleasing. I think that like much else in the world, mostly you get what you pay for...

 

[dogofwar]

People more artistically inclined than me have built dump filters (with Pothos, Peace Lillies and the like growing out of them) with plastic window boxes like these.

Home Depot has a 36" one for like $10...

Basically just drill a hole in the bottom for the powerhead to pump water in...and a couple on the other side for drainage. Fill with fluff, bio media, plants and herbs...and you're done!

 

[rich_one]

On my two 125s, I use FX5s and and AC110s. The FX5s have been great for me. About once a month (okay... sometimes it gets kinda close to two months), I rinse all of the foam inserts and bio media in tank water, and I change out any carbon I may have inside. Honestly, it takes me maybe 15 minutes per filter. I sit it in the tub, pour out the water, pour in more tank water, squeeze the foam inserts and repeat maybe 3 or 4 times. Hasn't been too difficult for me, and I've been using FX5s for over 2 years now. I use the AC110s both for just additional filtration... I like to over filter... and also for surface agitation. That's my method, anyway.

-Rich

 

[Sonny Disposition]

Yeah, it's really easy to patch a drilled tank. All you do is cut a square of glass about the size of the hole and silicone it over the hole on the inside of the tank. Let it cure and it's good to go. If it makes you feel secure, silicone another glass patch on the hole on the outside of the tank.

If the hole is on the tank bottom, no one will see the patch after you cover it up with gravel or sand.

 

[WendyFish]

We have a few different types of filtration going.

Our 55gall is filtered with canisters. We clean each of them every 3-4 weeks, and as Sam said, it's not a huge endeavor. Disconnect, dump the water, rinse the trays, put it back together, done. They are quiet. They are basically idiot proof, which because I'm not the mechanical genius in the family, is something I value.

We run sumps on our 110s in the living room. Yes, they can be made quiet, though it takes a fair amount of engineering and pure work. Though we're having trouble with one of our return pumps running loud right now, in general, ours run just about silently. I love sumps. They provide good optionality for a lot of things -- you can plant it, you can keep little stuff in it, be it shrimps or fry or whatnot. Sumps also oxygenate the water a great deal because of how they move it around. I imagine my fish enjoy this a great deal.

However, on the downside, my feeling (and experience) is that sumps are chaotic systems. They can fail in a number of ways, and no matter how many of those ways you have thought of and addressed, your sump can come up with a different one. (For us, it was that our overflows weren't watertight, so more water overflowed into the sump than the sump had room for.) It is, indeed, very sucky when your tank dumps a bunch of water on the floor (even more so when you don't have power to facilitate its drying). One safeguard we have put in place to address this is pretty simple -- water alarms. They get wet, they make a horrible sqeal, and you can stop whatever the problem is before it gets out of control.

HOBs, I don't get it. We've had a couple sizes of ACs, and I have not liked them. The impellers were crap on multiple units that we've owned. And they run loud IME, can always hear the water flow.

Tony mentioned Poret foam -- we really like this (you can Google mattenfilters for more info). We do this in our smaller tanks, but like it well enough that we'd consider it in a larger tank if we were ever redoing one or getting a new one. I'm at risk of butchering this horribly, because my job in the fish keeping equation is the livestock not the systems, but the basic premise is you put a big piece of foam in the tank, make sure that water circulates through it, and then bacteria grow in it and it filters your water. They're simple to set up and work well. No noise. You have to think about it a bit, but you can disguise it so that the tank still looks nice. Couple ways to do this, install it behind a piece of 3d or slimline background in the tank, or you can plant it. The plants will root into the foam, and the foam will still do its filtration job. They are a bit of a hassle to clean because pulling them out of the tank makes a huge mess (some of the funk stuck in them inevitably goes into the water), but they don't need to be cleaned very often. IME they are not as good as some other methods for mechanical. Expect to have to vaccuum more than you might with canisters.

 

[Jefft]

Awesome amounts of information folks thank you so much!

 

[MonteSS]

I have an Ehein 2026 canister on two different 75g's as well as an ac110 hob on each. Pretty heavily stocked and water is crystal clear and good water parameters with weekly 50% water changes.

I "open" the Eheim every 4 months and it takes 5 min to clean. Both are 5 years old now and totally silent and not a single prob.

I also use Jager (eheim) heaters exclusively and never had one fail.

....Bill

 

[dogofwar]

Just because they're out of sight doesn't mean the cakes of poop and uneaten food covering the mechanical filtration in a canister are somehow inert or not loaded with the same organics that many folks would get rid of immediately if they were visible or easily accessible (say, on the gravel, in a box filter, sump or HOB). Poop and uneaten food are poop and uneaten food. And removing them before nitrifying bacteria need to break them down is a good thing (less dissolved organics in the tank / nitrates).

I try to change the fluff in my box filters every week (more often in heavily stocked ones). It just takes a moment when I'm refilling after a weekly water change. Changing a tray of fluff in one of my dump filters similarly takes moments (and I do it every couple of weeks or as needed)...

The FX5 on my 180g (that powers the dump filter), on the other hand, ends up being a monthly pull it out and tear it down PITA, at least in relative terms. I know I should do it more often, but I don't. Which is why I don't like canister filters.

Matt

 

[Avatar]

Oh goody - a technical row...

Just because they're out of sight doesn't mean the cakes of poop and uneaten food covering the mechanical filtration in a canister are somehow inert or not loaded with the same organics that many folks would get rid of immediately if they were visible or easily accessible (say, on the gravel, in a box filter, sump or HOB). Poop and uneaten food are poop and uneaten food. And removing them before nitrifying bacteria need to break them down is a good thing (less dissolved organics in the tank / nitrates).

Perhaps, but I'll wager the "brown sludge" that accumulates in an Eheim using a pre-filter is about as "broken down" as it can get, that is to say, zero nitrites and very very low nitrates, which is to say, basically dirt and of little to no import to the occupants of the tank. Why? Because firstly poop and uneaten food can't get in there without passing through the pre-filter first (where nitrogen breakdown begins) and then afterwards they enter a chamber that is basically a dedicated de-nitryfying engine. Poop and uneaten food are just that to bacteria - food: to imagine that they go undigested inside Denitrification Central HQ doesn't hunt. Secondly, nitrites and nitrates are water soluble, and as long as water is flowing through the filter they do not/cannot accumulate inside the filters and are exported either through gas exchange with the air and/or during water changes.

I try to change the fluff in my box filters every week (more often in heavily stocked ones). It just takes a moment when I'm refilling after a weekly water change. Changing a tray of fluff in one of my dump filters similarly takes moments (and I do it every couple of weeks or as needed)...

I broke down 4 large Eheims just last week after over year without even looking inside them. During that year+, there were zero health issues with the fish in the tanks (despite repeated intervals of several weeks without any water changes) which include discus, and the water in one of the tanks was apparently good enough to induce Biotodoma cupidos to spawn several times. But wow - staggering amounts of brown sludge in the bottom of the canisters and particulate saturated filter pads/fluff. Rinsed all in buckets of tank water (including the fluff) and hooked it back up. But all that sludge is spent - I'd bet money I could have poured it all right into the tank with no ill effects on the inhabitants and an hour later it would have been crystal clear again because the bacteria have already digested everything available that it once had to offer. And because the resulting nitrates were exported during water changes.

How many times have you seen neglected tanks with particulates 1/4"+ deep everywhere with fish that are apparently just fine? The nitrates in those tanks are doubtless high due to the absence of water changes, but those nitrates are in the water not in the detritus which has been cycled for if it wasn't the fish would all be dead. When I went to visit Chris Moscarell (the Apisto breeder who spoke to CCA some months back) and who has a water purification system in his basement that would make many municipalities blush, he showed me some Apisto spawning tanks where "organic" material literally cascaded off of the plants whenever they were disturbed. Bottom line is that if the denitrification is happening along with water changes, this stuff is simply of no consequence beyond whatever aesthetic challenge it may represent.

The FX5 on my 180g (that powers the dump filter), on the other hand, ends up being a monthly pull it out and tear it down PITA, at least in relative terms. I know I should do it more often, but I don't. Which is why I don't like canister filters.Matt

Which is precisely why I use pre-filters and Eheims, religiously and exclusively respectively. For my money and periodically limited/zero time, there's not a more reliable and hassle-free system than quality canisters with pre-filters. But each to thine own, and blessed be bacteria that do all the work (except unfortunately for water changes).

 

[MarkK]

Which is better...

So what offers the best filtration of water for the fish HOB, Canister, or sump?

The issue with canisters is that they can be a pain to take apart and set up again and for that reason some people tend to run them longer than they should so for that reason HOB filters might be a better choice because they are so easy to maintain.

Having said that, it is important to maintain biological filtration media in such a way that you are not starting over in each cleaning.

I think a good approach is to pair a good quality sponge filter with a HOB filter and clean them alternate times.

 

[dogofwar]

Pre-filtration with canisters is indeed the key to reducing the need to constantly clean them...but you (of course) need to clean the pre-filters.

What do you use? Poret or something else? My only remaining canister is an FX5, which is indeed a beast of a water mover and uses pieces of Poret-like foam inside. I'm concerned that a pre-filter would reduce the amount of flow.

As an aside, I have routed the outflow of the FX5 into a 18g clear Rubbermaid filled with bioballs, 6" deep of Poret and a layer of fluff (for mechanical filtration). It's amazing how much brown stuff that collects on the outflow side of the FX5!

Reducing the amount of poop/uneaten food that accumulates in a tank system by cleaning the mech filtration and siphoning it off of the bottom (or reducing the amount of food and waste products through fewer fish / fewer feedings, etc.) is the way to reduce the amount of ammonia added to the system.

Less waste = less waste that's converted to nitrate and "cleaner" water...and the equivalent water change on cleaner water results in even cleaner water (less bad stuff to dilute).

I think of cleaning the fluff in my box filters sort of like siphoning the crud in the (sparse) substrate. If it's in the box filter, it's not in the gravel.

Just to hard to do with a canister, in my opinion....

Matt

Perhaps, but I'll wager the "brown sludge" that accumulates in an Eheim using a pre-filter is about as "broken down" as it can get, that is to say, zero nitrites and very very low nitrates, which is to say, basically dirt and of little to no import to the occupants of the tank. Why? Because firstly poop and uneaten food can't get in there without passing through the pre-filter first (where nitrogen breakdown begins) and then afterwards they enter a chamber that is basically a dedicated de-nitryfying engine. Poop and uneaten food are just that to bacteria - food: to imagine that they go undigested inside Denitrification Central HQ doesn't hunt. Secondly, nitrites and nitrates are water soluble, and as long as water is flowing through the filter they do not/cannot accumulate inside the filters and are exported either through gas exchange with the air and/or during water changes.



I broke down 4 large Eheims just last week after over year without even looking inside them. During that year+, there were zero health issues with the fish in the tanks (despite repeated intervals of several weeks without any water changes) which include discus, and the water in one of the tanks was apparently good enough to induce Biotodoma cupidos to spawn several times. But wow - staggering amounts of brown sludge in the bottom of the canisters and particulate saturated filter pads/fluff. Rinsed all in buckets of tank water (including the fluff) and hooked it back up. But all that sludge is spent - I'd bet money I could have poured it all right into the tank with no ill effects on the inhabitants and an hour later it would have been crystal clear again because the bacteria have already digested everything available that it once had to offer. And because the resulting nitrates were exported during water changes.

How many times have you seen neglected tanks with particulates 1/4"+ deep everywhere with fish that are apparently just fine? The nitrates in those tanks are doubtless high due to the absence of water changes, but those nitrates are in the water not in the detritus which has been cycled for if it wasn't the fish would all be dead. When I went to visit Chris Moscarell (the Apisto breeder who spoke to CCA some months back) and who has a water purification system in his basement that would make many municipalities blush, he showed me some Apisto spawning tanks where "organic" material literally cascaded off of the plants whenever they were disturbed. Bottom line is that if the denitrification is happening along with water changes, this stuff is simply of no consequence beyond whatever aesthetic challenge it may represent.



Which is precisely why I use pre-filters and Eheims, religiously and exclusively respectively. For my money and periodically limited/zero time, there's not a more reliable and hassle-free system than quality canisters with pre-filters. But each to thine own, and blessed be bacteria that do all the work (except unfortunately for water changes).