# DIY: re-plumbing ac50 HOB



## aspects

this is my first attempt at a smaller hob, so bare with me. i have done many ac110 and canisters in the past, but this is a bit smaller. same concept though.

the HOB filter is a great idea. and works great for most aquarium systems, however there is a major flaw in the design. with the intake tube directly under the silde (waterfall portion of the filter), youre recycling a lot of clean water that just came out of the filter. im not sure about the exact math, but id be willing to say its AT LEAST 50%.
by moving the intake to the opposite side of the tank, you create a larger cycle area in your tank, and maximize efficiency of your filter.

lets go.

what youll need:

























- aquaclear 50 HOB filter. (if im not mistaken, the AC30 also uses a 1/2" intake.
-1/2" pvc ($2 for a 10' pipe at home depot)
-2 hose clamps (though i only ended up using one. more on that later)
- 1 1/2" end cap for the pvc ( $.20)
- 1 1/2" 90 degree elbow ($.30)
- 5/8" tubing. you can usually find this for sale at your LFS. and if i remember correctly, they sell it by the inch. you will only need about 2" for this application.
- silicon (i dont use it, but you can if you want to make sure everything is tight.)
- a chop saw or hack saw with a fine toothed blade. (the finer the tooth pattern, the less likely you will have any problems cutting the PVC)
- a drill (with drillbit)
- a pot for boiling water ("what the hell is he talking about?!?!?!?")


first the measurement. i did this DIY for a 20L, so if youre using a different size tank, you will need to adjust it to fit.
this isnt an exact science, so, while you could get out the tape mesure and actually measure everything out, i found that eyeballing it was just fine.
you will need 2 pieces of PVC. one that runs the length of the tank, and one thats about 2" shy of the height. again, not an exact science, so you will have to adjust a little to fit your needs.

after you cut the 2 pieced of PVC to length. you will want to put on a pot of water and get it to a boil. 









more on this in a minute...

while your water is coming to a boil. get your drill, and put a few holes in the far end of the longer piece of PVC. (the side away from the intake)










after you holes are drilled. clean out any debris from the inside and around the holes. id suggest giving it a good rinse to be sure. then place your endcap on the drilled side, and 90 degree elbow on the other. make sure you assemble it so that the holes face forward, and the elbow is facing up.











is your water boiling yet?

take the intake "U" tube off the filter. you will also need your hose clamps and the shorter piece of pvc.










with a pair of tongs (i use my fingers, but you might not want to get that close to the boiling water) stick the piece of tubing in the boiling water. just a few seconds should be long enough to soften it up.

when the tube is soft, slip it onto the end of the "u" tube and the end of the pvc. and clamp with hose clamps.










(the hose i used was thick, so the second clamp didnt fit. but also, the squeeze was so tight to get it on, it wasnt necessary)



and thats about it. assemble the pieces of PVC and reattach the "u" tube to the HOB. 
this is where you would want to use the silicone if you want. i find its overkill though. and if you do use the silicone, you will need to let it cure for 2 days before filling the aquarium.

since i didnt, it was fill and go for me. lol








































happy with his new home
















thats all folks. all thats left to do is rock out!


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## trashion

Very cool!


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## aspects

heres a larger verson i did for my fry tank. (ac110)


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## joeeey

Nice improvement!


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## jones57742

as: This one is just unbelievable to Ron! ie. you really done good!



aspects said:


> the HOB filter is a great idea. and works great for most aquarium systems, however there is a major flaw in the design. with the intake tube directly under the silde (waterfall portion of the filter), youre recycling a lot of clean water that just came out of the filter. im not sure about the exact math, but id be willing to say its AT LEAST 50%.


You got this one nailed! and I anticipate that your 50% represents a minimum value.


A few comments and a question.



aspects said:


> by moving the intake to the opposite side of the tank, you create a larger cycle area in your tank, and maximize efficiency of your filter.


Your intake is at the rear of the tank.

In order to accomplish your goal should the intake not be at the front right corner of the tank?


I am currently operating two very rudimentary HOB's and their impeller shafts are magnetically driven. Via attempting to help out other folks I believe that magnetic drives are common for HOB's.

Is you pump magnetically driven and if so "where in the world" do procure it from?


Your intake orifices are at 0D (ie. horizontal where 90D would upward vertical). If these orifices are ultimately covered by aggregate would not a -45D or a 135D rotation be appropriate?

TR

BTW as: Thanks a bunch for publishing this thread as it has been very enlightening!


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## emc7

> believe that magnetic drives are common for HOB's.


 Powerheads & canister filters too. It seems to be the standard now to have the motor sealed in epoxy (waterproof) turning a magnet on a impeller. This is change from the old style dynaflows, Aquakings, & superkings that had an actually metal shaft running from the motor to the impeller. The were exposed so you could oil them, too. The good about magnetic drive is that if the impeller jams, you don't destroy the motor. The bad thing is you won't necessary know the impeller has stopped turning. You don't hear the bearings screaming like the old filters did. So air, plants, rocks or snails can stop the filter without an alarm sounding. 

One thing I never liked about the whispers is that there is no fixing the filter, the motor is part of the box and you have to throw the whole thing away if it fails. Some of the newer filters have snap-on motors like the old dynaflows did. So if you crack the box or kill a motor, you replace the part. 

This project is interesting. I would like to put a flow-meter in-line and see how the extended tube affects the throughput of the filter compared to the OEM intake. Also, are you having any trouble with debris building up in the tube or the elbows? I suppose you could always put a hunk of foam over the intake holes. I've always wondered what those sponge pre-filters do to flow. I know they restrict it less than other fry-barriers I've tried such as panty hose.

It reminds me of what people make for loach tanks, with power heads at one end of the tank drawing water thru PVC the length of the tank with a sponge filter intake at the other end. 

I wonder is there is an market for your extended intake. You could make them to fit standard size tanks.


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## aspects

jones57742 said:


> A few comments and a question.
> 
> 
> Your intake is at the rear of the tank.
> 
> In order to accomplish your goal should the intake not be at the front right corner of the tank?
> 
> 
> I am currently operating two very rudimentary HOB's and their impeller shafts are magnetically driven. Via attempting to help out other folks I believe that magnetic drives are common for HOB's.
> 
> Is you pump magnetically driven and if so "where in the world" do procure it from?
> 
> 
> Your intake orifices are at 0D (ie. horizontal where 90D would upward vertical). If these orifices are ultimately covered by aggregate would not a -45D or a 135D rotation be appropriate?
> 
> TR
> 
> BTW as: Thanks a bunch for publishing this thread as it has been very enlightening!


actually, because the water falls down and forward, it will, for lack of a better explanation, bounce off the front of the glass and back towards the back. creating a sort of circular motion back to the intake.

as for the magnetic drive, im not sure what exactly youre getting at, but yes it is a standard magnetically driven impeller. also, its not seald, making it much easier to clean. (every 3 mo or so, i take it apart and clean it)

if by "aggrigate" youre referring to substrate in the tank, you would shorten the down tube and have it sit on top of the substrate rather then bury it and have the holes facing up. that would probably cause all kinds of clogging problems.


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## aspects

emc7 said:


> Powerheads & canister filters too. It seems to be the standard now to have the motor sealed in epoxy (waterproof) turning a magnet on a impeller. This is change from the old style dynaflows, Aquakings, & superkings that had an actually metal shaft running from the motor to the impeller. The were exposed so you could oil them, too. The good about magnetic drive is that if the impeller jams, you don't destroy the motor. The bad thing is you won't necessary know the impeller has stopped turning. You don't hear the bearings screaming like the old filters did. So air, plants, rocks or snails can stop the filter without an alarm sounding.
> 
> One thing I never liked about the whispers is that there is no fixing the filter, the motor is part of the box and you have to throw the whole thing away if it fails. Some of the newer filters have snap-on motors like the old dynaflows did. So if you crack the box or kill a motor, you replace the part.
> 
> This project is interesting. I would like to put a flow-meter in-line and see how the extended tube affects the throughput of the filter compared to the OEM intake. Also, are you having any trouble with debris building up in the tube or the elbows? I suppose you could always put a hunk of foam over the intake holes. I've always wondered what those sponge pre-filters do to flow. I know they restrict it less than other fry-barriers I've tried such as panty hose.
> 
> It reminds me of what people make for loach tanks, with power heads at one end of the tank drawing water thru PVC the length of the tank with a sponge filter intake at the other end.
> 
> I wonder is there is an market for your extended intake. You could make them to fit standard size tanks.



because the tubing is the same ID as the OEM intake tube, i have no buildup in the elbows or tubing. and ive tested a few of my builds, and it does not seem to effect the flow. what would matter more would be how many holes/ slots you put in the tube. and because of the design of the aquaclear filters, there is no need for a prefilter or inline sponge filter. also, the aquaclear filters have a flow adjustment, so even at the lowest adjustment its able to filter this tank. and at the lowest adjustment it also uses a patented water recirculation system inside the filter which recycles about 50% of the water taken in, through the filter media multipul times before its sent back out the top. its a pretty impressive system if i must say. i however keep it on the highest adjustment, which is rated for a 50g tank. the arowanas in there seem to enjoy the ectra flow, and it keeps the tank really clean. 


i have done quite a few builds for friends but never went as far as selling it. because its such a simple DIY, i doubt there is a retail market for it. id rather just share the information with the community for free.


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## gil_ong

i've thought about re-routing the intake too.

one thing i have not worked out is the drag assocaited with so much pipe! how much more stress and i putting on the DC motor?


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## Cacatuoides

I DIYed!  I got it done yesterday, i think i need bigger holes or alot more of these, but it works, its running right now.


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## aspects

gil_ong said:


> i've thought about re-routing the intake too.
> 
> one thing i have not worked out is the drag assocaited with so much pipe! how much more stress and i putting on the DC motor?


from what i have notices in all the ones i have built in the past, there is little to no drag at all. i havnt tried an inline meter or anything, but i have put 2 filters sid by side and monitored operation, and noticed no visible or audible difference whatsoever. and i have had some of thises set-up's running for over 2 years with no added wear on the filter.


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## gil_ong

awesome. that's good to know. i might just have to relocate my surface skimmer.


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