ASM G-3 Skimmer Recirc Mod

[Teaggs]

I am looking to do this mod to my asm 3. Few questions...

Will it take up more room in my sump?

How many and what size bulkhead should I order to do the whole job? Aquacave or BRS to order them? If I use the s b ulkheads, then no pvc cement needed for the job, right?

Can I use my sedra 5000 pump since I have the mesh mod on it or do I need a lower gph Maxi jet?

I think everything looks self explanatory.

 

[Arthur1]

Teaggs, long time no see! I hope John chimes in and makes any needed corrections bc I had to look at some old pics for reference but it looks like I used 2, 1'' uni seals for the sedra pump and then I personally used a 3/4'' uni seal with a very short length of 3/4'' pvc going into it attaching to a 3/4'' 90, then I had a barbed fitting threaded into that, connected to vinyl tubing connecting to the maxi jet pump. I hope that's clear :beer: snd and answer your question, yest it will take up a little more room in your sump but if you have the room, its worth it.

 

[JohnV8r]

You need one 1" uniseal to attach the recirc part coming off the Sedra pump. You already have one 1" uniseal that comes with the ASM G-3. That is why you only need to purchase one 1" uniseal.

The second uniseal will be your choice depending on what you use for an intake pump. My MaxiJet 1200 uses 1/2" tubing. If you intend to use a 1/2" PVC 90 degree elbow fitting in a 3/4" uniseal, you're going to have a bit of an issue. 3/4" PVC has an outer diameter of 7/8". That will be too tight for a 3/4" uniseal. The last thing you want to do is try to force 1/2" PVC into a 3/4" uniseal that will put too much pressure on the skimmer body and cause it to crack eventually. HOWEVER, if you use a 90 degree elbow PVC fitting with a barbed hose fitting you can usually extend the barbed hose fitting through the uniseal. Just check the barbed 90 degree fitting in the 3/4" uniseal prior to cutting the intake into the skimmer body. Alternatively, you can use a Dremel or other sanding tool and trim down the 1/2" PVC fitting. There is no pressure in the PVC fitting, so you can shave off 1/8" without damaging the fitting...but it's a pain to shave them down.

All of that sounds more daunting than it really is. Just check everything BEFORE you cut the hole for the intake uniseal.

I ordered from AquaCave because they had the ASM uniseal which matches the curvature of the skimmer body.

Good luck.

 

[Teaggs]

Hey john I sent you a pm. Thanks

 

[JohnV8r]

I don't have anything yet....

 

[Teaggs]

I just sent it.thanks

 

[JohnV8r]

Responded.

 

[McPuff]

Here is my recirc. mod for my Warner Marine skimmer.



It was a bit more work than I had hoped... the fittings were all metric (I believe) so I had to carve out a few of them to accept English fittings. But in the end, everything fits and seems to work well. Drilling into the skimmer body was a bit nerve-racking but went quite well. Practicing on a spare piece of acrylic and/or PVC is definitely a good idea and will ease your concerns.

I ended up using a MJ 750 for the feed pump. I'm unsure if this will be enough flow for a 120 gal but I will have to wait and see how it works out. The sedra 9000 pump is definitely strong enough for a recirc pump (used to be the main pump and would cause overflows once in a while... lately, about once every two days... thankfully those days are over!).

One thing I have noticed thus far: I finished the mod last night and ZERO skimmate was produce overnight. There was an immediate production of foam but really nothing this morning in the neck. I suppose there are a couple possible reasons for this... 1) coincidence, 2) I had to clean the skimmer so perhaps it will require another break-in, 3) not pulling in enough air???, and 4) skimmers don't do much at night? I don't know why this should be any different than before but I'm not familiar with recirc. skimmers.

If anyone has any thoughts on the above please do share. I will do some more reading on the matter as well.

 

[JohnV8r]

I did not experience another break-in period with mine. I saw the really nasty dirty skimmate in the pictures at the beginning of this thread almost immediately. You may experience something different because you have a different brand of skimmer. I'm really not sure what to expect as my frame of reference is entirely ASM.

The one thing I noticed in your picture was that you are using clear plastic tubing in a configuration that is longer than the stock ASM tubing. That could be a source of trouble.

Clear plastic tubing is usually suited to positive air pressure from air pumps that push air through the tubing. It does not fair as well in negative air pressure where air is being pulled through the tubing. It can cause it to collapse or narrow. A longer piece of tubing only makes matters worse.

The venturi is a little bit more of an unknown. I'm assuming that is the stock venturi for your skimmer brand. The engineering of the ASM venturi is one of the key pieces to the design of the skimmer. Any venturi is very sensitive to changes in air flow. For example some people several years ago tried to drill out their ASM venturi thinking it would enhance the amount of air/bubbles mixed with the water. That actually backfired and decreased the skimmer performance.

As for the MJ 750, there is information available from Randy Farley that says if you try to increase dwell time (the time the bubbles are in the water) by decreasing the intake volume, you can actually decrease skimmer performance because it causes more time for the bubbles to collide with each other. That causes the air bubbles to release the proteins/nitrate from the air bubble and thus it does not get skimmed out of the water. Intuitively, you would think the more the same body of water was in the skimmer body the more clean it would be. However, Randy's research showed a counterintuitive result.

I ran an MJ 900 and thought I got better performance than I did with an MJ 1200, but switched to the MJ 1200 after reading Randy's article.

Give your skimmer a day or two and see what happens.

What are your nitrate levels currently? Testing now and again in a couple of days to actually see what the water quality is will be more revealing than the amount of skimmate produced.

 

[McPuff]

Well crap, that's a lot of possible problems...

Air intake - I have been using this clear tubing for a while now and it was always fine. It's 1/4" so does not seem to compress as you might expect from the finer air tubing. But who knows. The venturi itself has been modified due to the original pieces not fitting properly with new fittings. However, the diameter of the fitting leading into the skimmer pump should still be the same. Perhaps one issue is the placement of the air intake. As you can see in the picture, I drilled the hole in the wider part of the female:male coupler. I may need to move this to the narrower area... maybe that's similar to the issue you spoke about where people were boring their venturis. This may act in a similar manner. In fact, I just did a quick search and I never had the stock venturi shown for the sedra 9000. From the looks of it, the air intake is at the narrow point of the pump intake... therefore, it should also have the strongest "pull" with respect to air. I believe that moving the air intake should help. I will give that a try and report back.

As for nitrates, the levels are <=1 ppm so not bad.

I appreciate the advice on feed pump as well. I will have to up-size to the 1200 as soon as I can. But first, the air intake...

 

[JohnV8r]

You might have an easier time just buying a replacement Sedra venturi from AquaCave. At least that way you know you've got the right engineering on the venturi.

 

[McPuff]

You might have an easier time just buying a replacement Sedra venturi from AquaCave. At least that way you know you've got the right engineering on the venturi.

Indeed. I'm going to try to move the intake first... if I do have to buy a new venturi I'll almost certainly need to redo the fittings as well. I appreciate the insight.

 

[McPuff]

Also, a couple spec questions about the venturi...

If I purchase a new venturi I would also need to replace the volute assembly. How does the venturi attach to this? It appears that both are female adapters; the volute has the threaded adapter and the venturi appears to be slip adapter on both sides. Will the venturi slide over the volute fitting? And then, how does the venturi attach to the skimmer body? It appears to attach directly to the ASM bulkhead but perhaps there is a short length of PVC that extends from the venturi through the bulkhead. If you could clarify this, it would help immensely as the venturi is sold as an ASM part.

And... good news regarding my re-modification... the air intake is noticeably higher and foam production is markedly increased. All I did was insert a 1/2" pvc through my home-made venturi to reduce the intake diameter and thereby increase velocity of water passing through. I also moved the air intake to the threads of the original PVC coupler and made sure to drill through the coupler and the 1/2" pvc inserted through the coupler. The air intake now comes directly from that 1/2" pvc. That probably sounds a lot more confusing that it really is. Bottom line, I have a suitable venturi until I decide whether or not to purchase the factory version.

 

[Reefvet]

The gate valve mod adds a PVC gate valve and PVC piping that fits in the outflow pipe on the ASM skimmers. It allows more precise control and also allows for the outflow to be directed into the sump for less water noise.

I have a Euro-Reef CS6-2 that I've been told is essentially the same as the ASM G3.

Perhaps you know ?

I'm thinking the recirculating mod should work just as well on the CS6-2.

 

[Teaggs]

John- I just wanted to say thanks again for all your help when we talked the other day. Your insight was very valuable to me. I completed the recirc mod today on my ASM 3 and so far so good. I also started the carbon dosing that we spoke about last week and its working out great.

 

[Reefer PT]

Mod ?'s

Mod ?'s

Thanks for your illustrations, they should help me do this. Any step by steps on the other mods? want to do it all while I've got it cleaned up. My big question is the materials for these mods is a bit over a buck and a half if you get a good gate valve and feed pump. Is it worth doing on a old G3 or is just updating to a new skimmer with these features a better option?
Thanks
Dave

 

[JohnV8r]

You should be able to do the mods for less than $50, assuming you have a MaxiJet pump laying around somewhere. An MJ 900 or 1200 can be had very inexpensively if you don't have one. Drs. Foster & Smith usually has very low prices on MJ's.

You don't need anything more than a Schedule 40 PVC gate valve. That's around $20 at Home Depot.

 

[ca1ore]

I have a Euro-Reef CS6-2 that I've been told is essentially the same as the ASM G3.

I'm a big fan of the ASM skimmers and have run a G3 (and a MIniG and G4+) for many years. I think the gate valve mod is very worthwhile and convenient but I never found the recirculating mod to really do much in terms of performance (couldn't get it to work at all on the G4) to the point that I now just run it as a pass through. Before cutting up yours you might want to check in on the big ASM thread.

 

[JohnV8r]

No question the gate valve mod is the most transformative. That's an interesting perspective on the recirc mod.

I did the mesh and recirc mods at the same time, so maybe that is why my experience was different. My skimmate production increased not only in volume, but the gooey, smelliness as well.

Either way, these are great skimmers.

 

[Legalreefing]

Great write up. Thanks for posting