My Uber Skimmer: an ASM G-3 Modification

george1098

New member
Hi All
I have a 90 gallon reef, pretty much just FOWLR for now, with a couple softies, but my goal is to make it an awesome SPS tank. Here’s a link to the tank log
http://www.reefcentral.com/forums/showthread.php?threadid=847805
As everyone knows, a healthy SPS tank needs powerful efficient protein skimming. I of course knew I was going to have to throw down the big bucks for a real skimmer sooner or later. I’ve also toyed with the idea of making a skimmer myself, but I really didn’t know enough about them as far as which design was best, and working with acrylic or PVC, so I chickened out. Instead I opted to go somewhere in between making my own uber skimmer, and buying one. I had read allot about the ASM skimmers, and some of the modifications that people have been doing on them, and I decided this was the approach I was going to take. ASM’s are needle wheel skimmers that are pretty low cost for the performance they offer. They are basically Euro reef clones, but use PVC bodies and Sedra pumps that help keep costs down, as opposed to cast acrylic bodies and Eheim pumps of the Euro reefs. I love euro reef skimmers, and by no means am I bashing them, but your skimmer doesn’t need to be pretty, it just needs to work.
Anyhoo, so after a little research I decided on the ASM G-3 skimmer to start off with. For the longest time I was going to go with the G-4X model, which was much bigger and much more expensive, but the G-3 eventually won me over because it seemed like the most bang for my buck, and I wouldn’t have to do any major sump modifications to be able to fit it in (12”x8” is the approximate footprint. The G-4X has a footprint of 14”x16”).
So anyway, here it is, the ASM G-3 right out of the box. The body is 6.5” in diameter, it stands 14” high (including the collection cup), and it comes with the Sedra 5000 needle wheel pump.
asmg3skimmer.jpg

and the needle wheel
needlewheel.jpg

I tried the skimmer out over night as it was. I did this A: because I wanted to see what the stock skimmer could do before modifications, and B: because I am hopelessly impatient by nature and I really wanted to see this baby running.
inthebox.jpg

I was happy with the performance, but I defiantly saw area for improvement.
First, the bubbles in the skimmer body were pretty big. Ideally they should be about as big as the tip of a bald point pen, and these bubbles were about the size of rice grains (if rice grains were round…). I had several ideas on how to improve this. Second. The adjustable arm was pretty hard to move up and down to adjust the water level in the skimmer. I thought a gate valve would help with this. And third, I notices allot of micro bubbles coming out of the skimmer exhaust. The gate valve would also help with this.
 
Fist things first. After I pulled the skimmer back out of the sump, I decided to bore out the venturi so more air could be sucked into the skimmer. Pretty easy to do as seen here:
bore.jpg

Now, this is probably the most popular modification people do to their ASM skimmers. It is called the recirculation mod. I fist read about it at www.asmskimmer.com . It is an incredibly simple way to juristically increase the performance of the skimmer. A stock needle wheel skimmer sucks water in from the sump with the main skimmer pump (the needle wheel) and the water gets processed once before it gets blown out of the exhaust tube. A recirculating needle wheel skimmer sucks water in from the bottom of the skimmer and shoots it right back in so the same water gets processed over and over which increases the dwell time (time the water stays mixed with the air) and thus the amount of sludge the skimmer can take our of the water.
The modification itself is fairly simple, but you’ve only got one shot at it or you ruin your skimmer. I simply turned the pump so the venturi was positioned up against the skimmer body, then I used a dermal to cut a hole in the skimmer body so the venturi could stick in. I also replaced the elbow that came with the pump and fed the skimmer with 1” PVC because the stock elbow was not long enough.
cup.jpg

Next, I had to make the new hole for the venturi water tight (or as close to it as I could. Its an in sump skimmer thank goodness, so its not all that important). At asmskimmer.com they use rubber seals called uniseals, which are basically flexible rubber bulkheads. If you can get your hands on one of them, it would be best, but I couldn’t fine them around here for the life of me, so I improvised. I took a 1” PVC coupling, and cut it in half. I then worked it on the belt sander to fit the outside of the skimmer body exactly. I used regular PVC glue to stick it to the skimmer body accept the venturi, and it worked perfectly.
recirc.jpg

Of course, on a recirculating skimmer, the needle wheel pump re-circulates the water, not feeds the skimmer, so another method has to be used to get the water from the sump into the skimmer to be processed. For this I took a ¾” male thread by ½” barb elbow fitting and cut a hole for it in the skimmer body. On the inside of the skimmer I glued (again after working it on the belt sander to match the contours of the inside of the skimmer) a ¾” female thread by ¾” barb elbow to accept the outside elbow fitting. I could now attach this fitting to ½” vinyl tube to feed the skimmer.
feed.jpg

Some people use small submersible pumps or a power head to feed the skimmer, but I wanted to feed it directly off the drain line from the main display tank. This is a great way of doing it because it doesn’t require another pump (which cost money and use energy) and it allows the nutrient rich water off of the surface of the display to be directly processed by the skimmer. Here’s a pic of the set up I used to run a tube of the drain line.
return.jpg

the vinyl tube runs to the skimmer while the 1 ½” PVC takes care of whatever water is left.
 
Finally there’s the gate valve, which was also incredibly easy to install. The G-3 uses 1 1/4” pipe for the exhaust, and I happened to have a 1 ¼” gate valve left over from an failed skimmer project so the decision was simple. Everything you see is dry fitted, no glue used.
gvassembly.jpg

and fits on like so
gatevalve.jpg

notice the small hole on the elbow fitting to the right. Ideally this should be a T fitting which will help eliminate micro bubbles from flowing out of the exhaust (bubbles float up while water goes down), but the plumbing store was all out of 1 ¼” T fittings, so again, I improvised.

The last thing I did was install a bubble cup (that’s what I’m calling it anyway). The bubbly water will be fired into this cup directly from the pump, where it will mix around before flowing upwards to make foam. This will help reduce turbulence in the skimmer body (above the cup) which will keep the bubble sizes down. H and S and bubble king skimmers use a similar design. I am toying with the idea of putting a bubble diffuser plate, like on the BK skimmers on top of the cup. What do you think?
cup2.jpg


Finally, here she is all assembled
done.jpg

I’ll let everything dry and test it in the morning.
 
I've been toying with this idea too. I have 2 extra Sedra 5000s i bought a few weeks back. I guess i need to find a cheap ASM and modify the crap out of it. I think ill try with my CSS too.... great pics man. Good job. BTW uniseals are avail at ASMSkimmers.Com

:)
 
"notice the small hole on the elbow fitting to the right. Ideally this should be a T fitting which will help eliminate micro bubbles from flowing out of the exhaust (bubbles float up while water goes down), but the plumbing store was all out of 1 ¼” T fittings, so again, I improvised."

The T isnt usually there to do anything about microbubbles. Its there to keep the output from being a siphon. If its a siphon, the water level in the skimmer will fluctuate as the sump level does, if its not, the gate valve determines height.
 
Looks good. Get some of the PVC 90's that have the threading on one side and you can eliminate that coupler between the gate valve and the 90. It will save you some space at least.

Eric
 
i just did the same thing to my euro-reef rs6-1. your bubble cup is allot better then the T i put into mine, i did put a T into where the water enters the skimmer to help break up the flow.

nice job
 
<a href=showthread.php?s=&postid=7878716#post7878716 target=_blank>Originally posted</a> by Jasen Hicks
I've been toying with this idea too. I have 2 extra Sedra 5000s i bought a few weeks back. I guess i need to find a cheap ASM and modify the crap out of it. I think ill try with my CSS too.... great pics man. Good job. BTW uniseals are avail at ASMSkimmers.Com

:)

If you have extra Sedra's lying around I'll be really mad at you if you don't try to mod a skimmer. I would love to add another needle wheel pump to my skimmer, but I just don't have the room in my sump. If you decided to get an ASM, go with the G-4 or G-4X, it has a 8.5" diameter as opposed to 6.5" that the G-3 has. And I looked into getting the uniseals from ASM skimmer.com but it would have cost me $25 for shipping alone for a $3 uniseal (to canada mind you) so as it said in the thread, I improvised. Thanks for the kind words though :)
 
<a href=showthread.php?s=&postid=7879451#post7879451 target=_blank>Originally posted</a> by outy
i just did the same thing to my euro-reef rs6-1. your bubble cup is allot better then the T i put into mine, i did put a T into where the water enters the skimmer to help break up the flow.

nice job

Wow, you're brave, I'm not sure I could have brought myself to cut up a euro reef skimmer.
 
<a href=showthread.php?s=&postid=7879128#post7879128 target=_blank>Originally posted</a> by perpetual98
Looks good. Get some of the PVC 90's that have the threading on one side and you can eliminate that coupler between the gate valve and the 90. It will save you some space at least.

Eric

Yes I hated how huge the gate valve extension was. As i'll explain in a later post, i actually ended up doing away the the gate valve completely
 
sounds pretty much like mine, I was worried about space restraits, and now that I see my G-3 in there I kinda wish I went bigger, although I'm super happy with it. More pics to come tonight
 
I have an idea to run by you guys. To avoid putting another hole in the skimmer body couldnt you put a "T" (or tap a pc of pvc) between the venturi and the pump?
 
So here it is back in the sump (fashioned from a $7 recycling bin) and running. Notice the lack of a gate valve. You’re eye’s don’t deceive you, it canned it. I found that the flow going into the skimmer came in waves since I hooked it up to the display retune line. This made the water level fluctuate allot in the skimmer with the gate valve controlling it, so I tried taking it off and using the slip pipe that is the standard way of water level control with the ASM’s instead. It worked great and the water level stayed just where I wanted it to. I kept the PVC that I used to hook up the gate valve to use as the exhaust pipe because it keeps things much quieter.
nogate.jpg


Here’s basically the same picture but 4 days later. I went away drinking… I mean camping…. For the weekend and came back to find a stinky surprise. A full collection cup! For the first time in my reefing ‘career’! I was pretty pumped, but man does that stuff smell bad.
skimmate.jpg

Guess it works!
 
<a href=showthread.php?s=&postid=7897258#post7897258 target=_blank>Originally posted</a> by adnup
I have an idea to run by you guys. To avoid putting another hole in the skimmer body couldnt you put a "T" (or tap a pc of pvc) between the venturi and the pump?


I like where your heads at, I think that might work.
 
I would highly recommend it. I've been amazed at how well mine is working and it has only been a few days. I'm already noticing changes in the tank. Far less oily streaks floating at the top of the display tank, water looks clearer, hair algae blooms are clearing up, less diatom growth, and the corals (of which i have very few right now) are nice and open and loving life. I actually live in Florida for a few months out of the year, If you still haven't taken the plunge by next winter, maybe I could offer some more encouragement when I am down there :p
 
looks good, my question is how you get that 4" (looks like 4") pvc ("bubble cup" ) in your body? does the entire tops come off the ASMs nowadays?
recirc mods are great ,personaly i think the cup is a very good simple mod that would beifit a lot of skimmers, good job.
 
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