Undergravel HOB Combo Concept

The instability of a small tank has me contemplating a larger tank. I'm thinking about a 30 gallon rimless cube.

A concept I haven't found discussed is using an undergravel filter with a HOB as the "power head." The suction from the HOB would go into the riser tube to provide the water movement through the substrate. Probably a sponge "sheath" over the connection point to keep small fish and betta fins from being sucked in. I envision a 1/8th - 1/4th inch gap around the HOB suction tube and the undergravel riser so not all the water is coming from the undergravel.

Years ago I had a HOB filter and I liked it, but it didn't keep the water as clear as the undergravel filter tanks I had before it. I like what the HOB offers adding crushed coral and mechanical filtration. Seems like this could be the best of both worlds. With a gap between the tubes allowing water to flow through, it might prevent the pump from burning out prematurely.

 

I have no experience with undergravel filters but the combo may be a bit much for a betta. Especially the longer finned ones, they can't really tolerate much current.

 

most folks would just use powerheads to drive the undergravel filter and skip the HOB. not sure how it works out, worth a shot to see how it goes though. I think you might be the last person on earth using an undergravel still though maybe go retro with some box filters. hahaha.

 

Hmmm. It's an interesting idea and in theory should work. How would you know how much water you are actually pulling through the gravel vs. the bypass? Maybe set it up with an adjustable valve system? I never thought that this extra drag on the intake may burn up the pump, but if it did that's not good.

Overall it seems like a lot of trouble, leaving some potential for issues. There's an easier, proven way to get you what you want with zero chance of problems. Just run both separate. A small HOB with adjustable flow, (like the AquaClear) along with the UGF set up as you normally would. I've done this often with great results. Agreed that the water in my UGF tanks are always more crystal clear than the others without. They also clear up almost immediately even after a rigorous gravel vacuuming and water change.

 

I have no experience with undergravel filters but the combo may be a bit much for a betta. Especially the longer finned ones, they can't really tolerate much current.

Too much current from the HOB or the combo of both? There's no current from the undergravel. I'd be relying on the undergravel for most of the biological filtration, so I could use a small HOB.

most folks would just use powerheads to drive the undergravel filter and skip the HOB. not sure how it works out, worth a shot to see how it goes though. I think you might be the last person on earth using an undergravel still though maybe go retro with some box filters. hahaha.

I predict undergravels are going to make a comeback! I'm an undergravel believer, but now I see the difficulty in buffering a tank with calcium using them...that's why I suggest the HOB.

Hmmm. It's an interesting idea and in theory should work. How would you know how much water you are actually pulling through the gravel vs. the bypass? Maybe set it up with an adjustable valve system? I never thought that this extra drag on the intake may burn up the pump, but if it did that's not good.

Overall it seems like a lot of trouble, leaving some potential for issues. There's an easier, proven way to get you what you want with zero chance of problems. Just run both separate. A small HOB with adjustable flow, (like the AquaClear) along with the UGF set up as you normally would. I've done this often with great results. Agreed that the water in my UGF tanks are always more crystal clear than the others without. They also clear up almost immediately even after a rigorous gravel vacuuming and water change.

There's no way to know how much water is going through the undergravel. Just like using a bubbler, we're not sure, but it's enough to keep the water in great shape. This concept should bring a lot more water through than a bubbler, but not as much as a power head.

Yes, if you put extra load on a motor, it can cause early failure...draws more amps that it was designed for. I'm not sure if this would be an issue or not. If it stops working, you can just drop a bubbler in the riser till you get a new one.

The reason I suggest this concept is if I have a Betta the powerhead might be too much for it. The overflow of a HOB might be too...I'm not sure. A sponge shealth between the riser and the suction tube would keep small fish and fins from being sucked in...also provide more surface are for biological filtration. So this would actually be three filters running off of the HOB suction.

 

I've measured UGF flow by dropping the water level slightly below the riser output. Catch the water with a cup or bowl while timing for 10-30 seconds and do the math.

from the late 60's came in at 25 gallons per hour per uplift with the 50 year old Silent Giant air pump. Times four uplifts for 100 GPH total. This is actual flow and is plenty, because as you know it's the huge surface area of the gravel that does the work.

You really don't need or even want too much flow here. I figure strong flow just makes it more likely the system will suck down any food that lands on the substrate before the fish get to it. As long as water is flowing through it's going to feed the BB. This is why when I have used powerheads in the past, I always used small units with an adjustable flow feature so I could turn it down.

I believe your HOB powered UGF idea is sound, and am sure it's been done. Please post if you do it. One thing to consider is by doing this you will no longer have the aeration from the air stones and may want to add one. A small HOB, especially if set to low flow to not disrupt your Betta, is not likely to aerate (by surface agitation) to the same level as UGF air stones.

 

Seems like a good idea, I still have a under gravel filter running in my 65 gal along with a canister filter i think their a fantastic source of BB and many people these days don't use them but it has many benefits for a aquarium. Some fish stores I visit still use them on there tanks. Hopefully they never become obsolete.

 

I've measured UGF flow by dropping the water level slightly below the riser output. Catch the water with a cup or bowl while timing for 10-30 seconds and do the math.

from the late 60's came in at 25 gallons per hour per uplift with the 50 year old Silent Giant air pump. Times four uplifts for 100 GPH total. This is actual flow and is plenty, because as you know it's the huge surface area of the gravel does the work.

You really don't need or even want too much flow here. I figure strong flow just makes it more likely the system will suck down any food that lands on the substrate before the fish get to it. As long as water is flowing through it's going to feed the BB. This is why when I have used powerheads in the past, I always used small units with an adjustable flow feature so I could turn it down.

I believe your HOB powered UGF idea is sound, and am sure it's been done. Please post if you do it. One thing to consider is by doing this you will no longer have the aeration from the air stones and may want to add one. A small HOB, especially if set to low flow to not disrupt your Betta, is not likely to aerate (by surface agitation) to the same level as UGF air stones.

Well, maybe if I have two riser tubes, I can do one with an air pump and the other with the HOB suction.

Seems like a good idea, I still have a under gravel filter running in my 65 gal along with a canister filter i think their a fantastic source of BB and many people these days don't use them but it has many benefits for a aquarium. Some fish stores I visit still use them on there tanks. Hopefully they never become obsolete.

I think undergravel is under appreciated.

Three concerns I'm aware of:
1. digger fish disrupt the substrate (I haven't dealt with this, so I don't know what say)
2. difficult to clean (there's a guy on youtube who builds them in a way that makes maintenance very easy)
3. not as easy to buffer the water with calcium rich media (crush coral, oyster shell)

I worked around 3, but it's not ideal. Two requires some DIY, but looks like fun.

Easy clean undergravel:

 

I use undergravel filters. They are great and are proven to provide great bio filter capacity.

The myths about them building up sludge, clogging, and then releasing the waste into the water is unfortunate. While this buildup does occur in a tank that is unable to process the waste load, in a balanced aquarium the waste build up reaches a steady state, the flow remains good and it does not need cleaning. The sludge is biofilm and is the bio filter.

When you insert your HOB intake into the UGF lift tube, you will need to seal it at the top. Otherwise the water will just flow in from the top of the lift tube and up into your filter. This path is much less resistance than pulling the water through the gravel so most of the water will be coming this way defeating your purpose.

As long as you seal it to force the water to come from the gravel, this will be a great way to power your UGF.

 

Well, maybe if I have two riser tubes, I can do one with an air pump and the other with the HOB suction.

My concern here is if not set up carefully to regulate the flow, a HOB could pull more than the air powered side and end up sucking water in from that uplift tube instead of only through the gravel. But it sounds like you have that worked out with your sponge sheath connector. Of course this potential for one side to overpower the other could be rendered impossible if two separate, unconnected plates were used.

I'm torn between intrigue over the idea, and thoughts that it'll be more trouble than it's worth. I certainly would like to see it if you do it.

 

I would agree that a UGF is under appreciated a lot of people think it's like the old days of fishkeeping a bygone era and not needed anymore, but i still think it has a lot of benefits for a tank. The plates protect the bottom glass, a great source of BB always there, pretty much last forever ,great to grow plants in many have said, also some people think that every now and then you have to take out the plates and clean underneath i never did that in the 20 years i had it on my old tank even when i had to tear the tank down to get a new one (the old one started leaking ) i was surprised to how there wasn't a lot of gunk underneath as long as keep up you syphoning should be fine. If anybody that is concerned about the bottom you can just put a power vac that picks up water down the tube, and it will suck up debris from the bottom.

 

I am a believer too testing showed UG with water pump beats HOB and canister.

I am using UG for crystal clear water in my 10 gallon. But it is air pump driven.

Would love to add a HOB to drive the UG!

 

Also a under gravel filter user in 3 tanks. They are a bit of a pain using airstones but work great using powerheads. Amazon still sells them so somebody must be buying them

 

I saw this UG on Taobao. It allows you to use a soft uplift tube (12mm or 16mm). it is used to attach the UG to a canister filter.

I guess you could attach the soft tube relaticely easy to the intake of an HOB. Since the tube is soft, it should be easy to get tight seal between the HOB's intake and the uplife tube.

what is the diameter of intake tube of a typical small HOB?

 

Also a under gravel filter user in 3 tanks. They are a bit of a pain using airstones but work great using powerheads. Amazon still sells them so somebody must be buying them

Right. Airstones clog up and stop working. Power head pulls way more water than an air stone and just keeps going. The strong pull from the power head also keeps the UGF clean and flowing so no maintenance needed.

Lots of the bad rap for UGF is from underpowered air stone lift tubes.

 

I use two undergravel filters each driven by a powerhead in each back corner of my Clown Loach tank.

I haven't added additional filters as my parameters are very low and my water very clear despite having digging fish.

Gravel vacuuming takes care of maintenance and I've replaced the undergravel filters twice in 27 years due to them becoming brittle over time. They cost peanuts. The Aquaclear powerheads are reliable.

I like having all the filtration inside the tank as in 27 years I may otherwise have had a leak possibly leading to the loss of my fish.

I see no disadvantages to warn about in my application.

 

I use two undergravel filters each driven by a powerhead in each back corner of my Clown Loach tank.

I haven't added additional filters as my parameters are very low and my water very clear despite having digging fish.

Gravel vacuuming takes care of maintenance and I've replaced the undergravel filters twice in 27 years due to them becoming brittle over time. They cost peanuts. The Aquaclear powerheads are reliable.

I like having all the filtration inside the tank as in 27 years I may otherwise have had a leak possibly leading to the loss of my fish.

I see no disadvantages to warn about in my application.

Hi Redshark1 . Do you have a thread about these fish and their tank you can link? I'd really like to see more. Thanks!

 

I would agree if one does want to use a UGF I would say to use a powerhead over the air stone as they do get clogged over time, also another good thing about a UGF with the powerhead is a constant current in the tank so parts of the tank don't get stagnant water and fish seem to like the currents from what I've noticed.

 

My current is nominally x 5 turnover. I found that x 10 turnover was too much and my Clown Loaches would not be able to sit on the gravel out in the open but would hide away. The x 5 and x 10 are specific to my tank and equipment.

I am using an airpump in another application which requires low current.