first attempt at air driven HOB

[Markp2483]

The idea started with me making a 3d printed overflow when i realized the overflow is a perfect basket for foam and filter floss.  I think its better to pull the water through filter media rather than pushing it and  siphon should do that without the chance of overflowing.

There is a union on the underside of just incase you need to disconnect overflow and get the siphon going again (tumble it around in a bucket or tank till the air comes out). The valve and cam lock is for clean out.  I've upgraded my python to camlock as some of the python fittings were leaking. Large chamber is to reduce the speed of the flow and allow for a more efficient airlift pump.  It also works as a nice place for bio media 

Con's I see

1) probably will need substantial airflow to get 200gal per hr which is the same as the current pump i have on the tank

2) Overflow is a surface skimmer so you need a ATO system.  (already in place for me)

3) kinda large and plumbing parts are expensive right now

 

I haven't decided if i'm going to make it but the overflow box is in production on craftcloud .  Ill test it out on the bench and see if everything works. 

What do you guys think?  

[Guppysnail]

This looks awesome. I would love to see video once it’s together running on a tank. 

[Markp2483]

well works pretty good.  nothing is glued so all the joints leak but I think it passes as  an air powered hob.  
 

[Markp2483]

Flipped the pipe around so it’s the right way

[Markp2483]

 

[MrGibson]

This is very cool! Do you have any stl/3mf or cad files you’d be willing to share so I could play around with this? No worries if not 

[Markp2483]

On 1/21/2024 at 12:34 PM, MrGibson said:

This is very cool! Do you have any stl/3mf or cad files you’d be willing to share so I could play around with this? No worries if not 

Sure here is an step file for the overflow. Bulkhead is a aquarium coop 3/4".  The airlift is a 3/4" jetlift i found on Esty, works good but the sockets aren't deep enough for proper gluing

overflow part 1 https://drive.google.com/file/d/1nByI4Ox8o0iC_F8phvjDwYCvVfAD2kmN/view?usp=drive_link

overflow part 2 https://drive.google.com/file/d/1fGbng40MXsahySwW1u8EDqINrJkOUs-i/view?usp=drive_link

This is set up for a rimless tank around 10mm thick so if your glass is thicker or a rimmed tank than you'll need to modify it. Also may need to vary intake height depending on where you keep your water level

I printed it out of ASA which i believe is a more UV stable ABS like plastic.

I really like how simple it is to start the siphon. Just submerge the in tank piece  rotate 360 till the bubbles come out and place into holder box.  I havent seen any overflow boxes this easy to start without pumps/airline tubes/disconnecting hoses etc   

 

 

[MrGibson]

On 1/21/2024 at 7:18 PM, Markp2483 said:

Sure here is an step file for the overflow. Bulkhead is a aquarium coop 3/4".  The airlift is a 3/4" jetlift i found on Esty, works good but the sockets aren't deep enough for proper gluing

overflow part 1 https://drive.google.com/file/d/1nByI4Ox8o0iC_F8phvjDwYCvVfAD2kmN/view?usp=drive_link

overflow part 2 https://drive.google.com/file/d/1fGbng40MXsahySwW1u8EDqINrJkOUs-i/view?usp=drive_link

This is set up for a rimless tank around 10mm thick so if your glass is thicker or a rimmed tank than you'll need to modify it. Also may need to vary intake height depending on where you keep your water level

I printed it out of ASA which i believe is a more UV stable ABS like plastic.

I really like how simple it is to start the siphon. Just submerge the in tank piece  rotate 360 till the bubbles come out and place into holder box.  I havent seen any overflow boxes this easy to start without pumps/airline tubes/disconnecting hoses etc   

 

 

Rad I’ll report back if I get around to messing with this! I’ve not printed with ASA yet but I’ve had some printed PETG parts in my nano reef for nearly 4 years now with zero problems. 

[nabokovfan87]

@Markp2483 Nice work.  I wonder what you're using this for.... What tank is it on permanently if any? 🤔

[Markp2483]

On 1/21/2024 at 5:42 PM, nabokovfan87 said:

@Markp2483 Nice work.  I wonder what you're using this for.... What tank is it on permanently if any? 🤔

Mainly it’s just a cool overflow, the hob part is me thinking what else I could use it for.  I’m planning to put it on a 30gallon planted tank. In the tank,  I have a sick praecox rainbow with a swim bladder issue waiting on her to pass before changing anything. She's a great fish and gave me a ton of fry. Not ready to euthanize as she still feeding ok.

[Markp2483]

Some updates

added a spillway box.  Could have 1 or two overflow boxes hooked up to it (one overflow on each side)

Spillway box could hold heater and bio media

overflow holds sponge and other filter media

Also working on new airlift pump design based on annular venturi injector (found a research paper)

[Markp2483]

Ive been slacking on this project

Updates

1) spillway box was a bit of a disaster.  The 3d printing company screwed up.  Part came out deformed and leaked like a sieve.  Made a new one and that seems to work need to remake the top as that was sized for the original one

2) new airlift pumps not working that great. Noisy, too big and with noticeable intermittent flow. Need to think more about that. Looking for a more consistent quiet flow

3) playing around with the idea of adding a sorta protein skimmer in between the airlift and spillway with a T.  I noticed in some of the koi pond videos that are run on airlift pumps they have this as a feature to remove foam. here is a screen shot from that video. https://www.youtube.com/watch?v=d0yL485-wlk

 

 

Here is short of what it looks like today https://www.youtube.com/shorts/AHihkt0Lk2w 

This is with the "T" for sudo skimmer just missing the cup. Doesn't seem to reduce performance

 

 

 

[Markp2483]

Todays update

1) lowered airlift pump as low as possible which really improves flow

2) overflow is now the limiting factor. The cross sectional area needs to be double the size ( 1 1/2 overflow and 3/4 return)

3) updated models and off for production 

here is quick video from today’s testing 

 

[lefty o]

great concept. here's some hopefully constructive criticism. looks great, works great as is, but it only takes water from the top of the tank. i myself dont care for that. now picture if you will the co-op sponge filter with the new pipe they put on them that will carry water up. make that stand pipe long enough to draw from the sponge filter all the way up, and dump into your HOB box where you have more filter floss or sponge or whatever. just my thoughts.

[Markp2483]

On 3/31/2024 at 9:03 AM, lefty o said:

great concept. here's some hopefully constructive criticism. looks great, works great as is, but it only takes water from the top of the tank. i myself dont care for that. now picture if you will the co-op sponge filter with the new pipe they put on them that will carry water up. make that stand pipe long enough to draw from the sponge filter all the way up, and dump into your HOB box where you have more filter floss or sponge or whatever. just my thoughts.

Understand about only taking in water from the top and yes could definitely modify to take in water mid water column.

here are the reasons

1) I run rimless tanks and hate seeing bio film oil slick on the surface. Airstone help but not as good as a skimmer.

2) I don’t know if it matters where you take in water.  You look at any tank with a sump or an Aio and they all only take in water from the surface.  I do think you need something down low to help with circulation so a wave maker/ powerhead hidden in the back down low keeps the particles in the water column until they eventually go out via the skimmer. 
 

3) access to used mechanical filter media. Intake sponges work great but I hate cleaning them, yes I know it’s the same as a sponge filter (ziplock bag trick) but I always make a mess. With the overflow I can just grab the sponge easily give it a quick rinse and back in. 
 

I think I will model up a version for lower intake as well. Maybe have a skimmer on one side and a pipe on the opposite both feeding into one hob box. I’ll make them interchangeable so can quickly change between a skimmer or pipe and see which I like best 

[Markp2483]

Maybe something like this. I like using siphon to get water out of the tank and then use airlift collar near the floor to pump water back into the tank. Gives you an extra 3 feet of tube length which massively improves flow rate/pump head and makes it quieter.  I think with this i should be able to tumble it around to prime the siphon and then carefully lift it up but keep the grating below surface to not break the siphon and place it in the box. Once in the box it should start to flow

[Markp2483]

Ok getting closer

new overflow box is working like a champ. Hooked it up to a 550gal per hour pump and couldn’t get it to run dry. So the overflow should stay nice an quiet.

the new airlift pump is working well but the outside has a few pin holes that I can see are leaking air and water. I’ll try coating the outside in epoxy that is ment to stick to abs. Will see if that works. 
 

I made a little extender to the hob part. The bubble right now are too close to the top of the edge and rattle the cover. It should also act as a bubble/ foam catcher. Should receive that by next week. 
 

Here’s a video of how it looks today

 

[Markp2483]

I've come to the conclusion that i don't think its possible to 3d print air and water tight parts particularly parts that are under hydrostatic pressure like an external airlift pump.  Im pretty sure if i installed it would eventually leak so for now i will abandon the one piece airlift pump and try to assembly an airlift pump from off the shelf parts and 1 3d printed part.

 

My return line is 3/4" pvc pipe. 

So i purchased a 1" tee,

2 x 1" to 3/4" reducer bushing,

1" spigot to 1/4" NPT bushing

Push to Connect Air Flow Control Valve, 6mm Tube OD x 1/4" Male Thread, Elbow 90 Degree Switch Valve

The last part is the key to the whole system.  It connects to standard 1/4" aquarium airline tubing and has a Chinese finger trap style mechanism that secures the tubing way better than a barbed connection.  The valve is great as it allows you to disconnect the air hose without worrying about leaking particularly important after i install inside my living room. This looks like the same fitting that GLA uses on some of there C02 reactors.   @Cory  If you were ever looking to update the AC gang valve push connect valves are pretty nice for fine tuning airflow.

 

 The next part i made was the airlift screen. I initially tried to make it with a 1mm drill bit and a bit of 3/4" pipe but after testing the bubbles looked too course so went back to the small slot pattern that ive found on most airlift collars.  Thankfully its super cheap to 3d print ~3 dollars.

 

Assembled the cross section looks some what like this although the actually parts are different.  Assembly below was created using the free 3d models you can get off mcmaster car website

Will update when i receive the airlift screen

Edited April 27 by Markp2483
last photo wasnt showing up

[Anchor_fist]

This seems like pretty cool idea, in fact it's giving me some ideas to try