Octopus Skimmer Mods

[rleechb]

Anyone ever increased the neck height on a NW150? I've maxed out the neck, but there's so much turbulence in the body that I feel it'd be much more efficient if the new was 3-4" taller

[1badbrd]

should i try and drill the venturi out a little and clue an RO line in to try and see if more air will add more bubbles and eventualy more foam

also i dont think i can add anymore mesh. I have maybe three layers.

Alos whats the lowest watts we want these things to go down to. Right now its about 56-58 depending on the level

[pogodzib]

JCTewks (I think) added an 18" extension onto his Octo skimmer at one point, but he ended up taking it off. He has been posting in the evenings so maybe he will respond to that question for you.

[1badbrd]

what exactly is the o-ring mod?

[flyguy7150]

Originally posted by 1badbrd
what exactly is the o-ring mod?

http://archive.reefcentral.com/forum...5&pagenumber=1
first pic...see how the big flat o-ring blocks the venturi hole? Mine being an in sump skimmer, i removed it totally. For a recirc, you still need an o ring there to prevent leaks. So he one of those round o rings, instead of the flat ones that came with it. When i first used my skimmer, i had the oring on, removing completely changed it.

[flyguy7150]

also, how big are you guys drilling that hole out?? Do you also drill out the nipple that connects the air line as well?

[1badbrd]

here is a pic of my needle wheel, i dont think i could add any more but as long as it runs without rubbing the inside of the case i;m fine correct.







also what size is too big for the venturi?

[flyguy7150]

that is what you guys drill out too right??? the red circled area

[luke33]

Well for the nw200, not the recirc you need to take the impeller and pop off the top layer of nw, then add imo 4layers of enkamat. Then tie it down tight. Now you need to take the venturi and put a 1/4" hose adapter very close to the volute cover with a slit cut aimed towards the impeller. Then boar out the elbo and you'll get 40scfh every time....if you do it right.

[flyguy7150]

i thought i read people drilled out those holes and had sucess getting more air???

[luke33]

Flyguy, yes you will get more air, but no where near the 40scfh.

[flyguy7150]

well did it, seems to be making much better foam, had to lower the riser a lil bit. Hopefully my kill a watt comes soon, want to add a third layer of enkamat. I did 2 already with out one .

[1badbrd]

well i drill a little too much and now i get a great sucking noise and the bubbles are being sucked back into the pump and the watts swing between 65-70 watts. I knew i went to big but once i started i said owe well if it doesnt work i will drive up to marine solutions and pick up a new peice.

3/8 was too big just to let you know.

Know the question is the stock hose fits a 1/4" barb fitting, so is the stock port 1/4"?
Why are people porting it out to 1/4" when a 1/4" hose fits on the stock fitting?

I just read that i needed to add a slit and aim it towards the impeller

[flyguy7150]

Originally posted by 1badbrd
well i drill a little too much and now i get a great sucking noise and the bubbles are being sucked back into the pump and the watts swing between 65-70 watts. I knew i went to big but once i started i said owe well if it doesnt work i will drive up to marine solutions and pick up a new peice.

3/8 was too big just to let you know.

Know the question is the stock hose fits a 1/4" barb fitting, so is the stock port 1/4"?
Why are people porting it out to 1/4" when a 1/4" hose fits on the stock fitting?

I just read that i needed to add a slit and aim it towards the impeller

3/8 for the the little hole of the pic i showed???? yea its way to big, even 1/4 is huge for that lol. AT least your close to MS

[JCTewks]

Originally posted by rleechb
Anyone ever increased the neck height on a NW150? I've maxed out the neck, but there's so much turbulence in the body that I feel it'd be much more efficient if the new was 3-4" taller

I did add an 18" extension to my DNW110, and it worked well when I had it on there...I have since removed it and am back to a stock neck, although I am considering working this new pump some more and putting it back on

If your problem is turbulence, you need to find a way to get less water through the pump, while maintaining as much air as possible. I had to add a neck extension not for turbulence issues, but because with the amount of air i had in there the water level in the skimmer was 3" below the top of the main body (below the bottom of the neck transition) and still overflowing the collection cup.

[JCTewks]

Originally posted by 1badbrd
here is a pic of my needle wheel, i dont think i could add any more but as long as it runs without rubbing the inside of the case i;m fine correct.







also what size is too big for the venturi?

It looks like your mesh could be a larger diameter...that will give you LOTS more air. I think that the thickness is fine. It may also be a little too tight.

The venturi os tricky...it really has little to do with the size of the actual airline feeding the venturi, but how the inside is shaped. You could put a 1" airline feeding it, but the venturi can only suck so much air...so you find what wiil work best for your particular application. sometimes it's 1/4:, sometimes it's 5/16 or 3/8. I found that 5/16" works well...but that is on the venturi's i've built.

[flyguy7150]

when you guys say you remove the top needle wheel, do you cut the needles or is there a way to pop em off?? IF so how do you get them off without cutting????

[pogodzib]

The needles are just glued on. Look at where you see the needles connected to the shaft closely and you'll see a line where the needle impellers are glued to the shaft. If you take a razor blade and go around the line, you can break the glue and then gently work the impeller up the shaft until it comes off. I find that a small screwdriver is good for this.

[rleechb]

Originally posted by JCTewks

If your problem is turbulence, you need to find a way to get less water through the pump, while maintaining as much air as possible.

Any ideas on how to do this? I was thinking about diy'ing a bubble plate of some sort... anyone done that?

[1badbrd]

are you performing this mod on the elbow that leads towards the pump. So this mod is before the pump, were on the stock otp3000 the venturi is after the pump?

I take this back i might have it backwards. This elbow is after the pump were the stock config has the venturi before the pump. Or is it because you are using a diffetent pump

Originally posted by JCTewks
Right now I am running 1layer of enkamat in between the 2 stock NW's and it is pulling 8scfh at 29watts on the OTP1000. These pumps are capable of much more air...but the dnw110 just won;t handle it.

I would say that you could safely do 1 layer between the NW's, trimmed to the diameter of the NW w/out a kill-a-watt. I do have a modded venturi though which alliows more air (less watts). The venturi mod is fairly easy on the DNW series.





I just used a grinding wheel on the dremel to enlarge the output side of the venturi, drilled through/enlarged the old airline fitting, and glued in a 1/4" barb x barb fitting that was cut at an angle on one end.

[1badbrd]

i'm heading to marine solutions tonight to pick up a couple of venturi connections and another impeller and see if i can get this skimmer to produce something before moving on to another skimmer. I think i will redue the mesh mod and try to alter the venturi, since i think i went too bid on diameter and i didn't angel the barb tip that goes into the tube.

[JCTewks]

Originally posted by 1badbrd
are you performing this mod on the elbow that leads towards the pump. So this mod is before the pump, were on the stock otp3000 the venturi is after the pump?

I take this back i might have it backwards. This elbow is after the pump were the stock config has the venturi before the pump. Or is it because you are using a diffetent pump

The Mod in the Pics si from my DNW110 where the elbow is the venturi and is before the pump. On the DNW200 the elbow is on the pumps output and the venturi is a straight piece. Boring out the elbow on the output will help get more water/air out of the pump and into the skimmer. THere are many better venturi's out there than the ones on the DNW series of skimmers, but with the right mods the stock ones can be made to work well.

[JCTewks]

Originally posted by rleechb
Any ideas on how to do this? I was thinking about diy'ing a bubble plate of some sort... anyone done that?

It's really all in the venturi! these pumps don't really have that high of a water throughput when meshmodded with the right venturi. THe key is the "smallest possible" (read loosely ) restriction that will get the most air draw. I think that a lot of people are boring the inside of the venturi out a little too large and getting high water throughput. with the right venturi mods, you can get the same (or more) air with less water flow. for the OTP3000 1/2"-5/8" seems to be close to the right size restriction with a 5/16" ID airline right at the point where the restriction gets larger (on the pump side). Remember when you are working with the dremel it's a lot easier to take a little more off later than to try and put some back in So, go slow and test your venturi's airdraw/water throughput often when trying to figure out the best one for your pump/situation.

Here is a rough drawing of what i'm talking about for the OTP3000 on the DNW200.

[1badbrd]

well a little feedback, i went with 1/4" ID barb, and i had to get the barb flush with the inside of the tube, just like your previous design describes. I also stripped my previous layers and just added one good layer. Before i start trimming down the volute i tried this combo and i have to say, this combo works 100% better then before. So good i dont think i want to try and trim down the volute and the port between the pump and skimmer. Maybe when i see the performance decrease i will touch it again, but i have to say i'm glad i messed with it.

Although iam curious how much better would it perform if i only bore out the tube in your diagram, just after the venturi. I dod notice there are a lot of different sizes from piece to piece, doesn't make scence, too many restrictions of flow.

PS. Marine solutions does not have venturi pieces for recir. skimmers, so dont destroy the stock venturi piece, it might cost a little more to replace. Also they received a bad shippment of impellers so i could get an extra and play around with different layers of mesh.

Thanks for the help people.

[GrandeGixxer]

badbrd, did you use enkamat or gutterguard?

On the DNW-110, what would taking the "T" /elbow/down tube off of the return and just having a pipe that comes out of the ball valve and overflowing back into the sump? Kinda like the ASM skimmers?