Octopus Skimmer Mods

[impur]

Can you post some pics of the impeller with the mesh?

[ppurcell]

Actually, I just did a quick test. I removed the volute from the pump and just pushed an airline tube down into the intake area. The air intake jumped up to 9-10 lpm and if I used my fingers to restrict the water intake a bit, I could get it to jump up to 11-12 lpm. So I think that solves part of the mystery, the volute opening is too small.

I'm going to go grab my dremel and start grinding out the volute out a little at a time until I get the flow up to 11-12 again.

[hounddog01]

Originally posted by ppurcell
impur, I agree something isn't right but I'll be damned if I know what it is.

I put the pump into a bucket to test so that there wouldn't be any head pressure. The pump only draws 7-8 lpm when it is running disconnected from the skimmer in 5" of water with no head pressure at all.

I use a SCFM meter. What is the difference between the lpm and SCFM

[ppurcell]

LPM = liter per minute
SCFM = standard cubic feet per minute

1 lpm = 0.3531 scfm
1 scfm = 28.32 lpm

you can do the conversions at this link:
http://www.memflow.com/conversion.html

[hounddog01]

So my skimmer is pulling 595 lpm. That is a long way from what your pulling. My opt 3000 pump pulled 10 SCFM out of the box. that is 283 with out any mods. What does yours pull with out the mods.

[Papajin]

FWIW, even if you're not planning to widen the volute opening, I found mine to have partial blockage due to debris being lodged in there. I'd recommend that all owners take a flashlight and check in there to make sure air is flowing freely.

[ppurcell]

hounddog01, I think you might be using SCFM when you should be using SCFH. I think it likely you are getting 10 SCFH which equals 4.72 lpm which is just about the same as my pump was drawing out of the box. You have to divide by 60 to get a SCFM measurement (which would be 0.1667 scfm and would not scale well on a hand held meter).

I don't think you could get one of these pumps to pull 283 much less 595 lpm. Typical measurements for a pump that is drawing a lot of air seem to be in the 30-45 lpm range (1800-2700 lph). It's confusing since everyone using different units of measure; lpm, lph, scfm & scfh.

So that would more likely be 21 LPH which equates to about 10 LPM; which is just about what I am getting now that I have removed the volute and am just using a 1" coupler with a JG fitting drilled into the side.

[hounddog01]

PPurcell, If your pulling 7-8 LPM which would equate to 14.8 - 16.9 SCFH (Which is what the meter is, Sorry about the confusion). Then you are a little low I pull about 22 (10.4) - 25 (11.8) SCFH (LPM) with my pump. It took about a week before I got the maximum draw from the pump. Have you done the venturi mod. I believe I got the same numbers you have before I did that and my current numbers after the venturi mod.

[ppurcell]

I'm getting about 11 lpm right now with the coupler. I'm going to work on the rounding out the edges on the output and add one more layer of mesh to the needlewheel to see if that helps a little more. I think if I can get in the neighborhood of 14 lpm that will be good enough.

[ppurcell]

Update on my ASM G4+/Octopus pump Hybrid project:

I spent a some time experimenting and re-working (ok, fiddling with) the intake on the OTP-3000 pump and think I have found the an effective combination to obtain mid-range performance with a steady 11-12 LPM (23 SCFH) air, and about 55-60 watts electric draw. This provides good slow water turnover through the skimmer, and provides a lot of bubbles in the reaction chamber without a creating a lot of turbulance. And you don't have to be a mechanical engineer or work in a machine tool shop to do it.

I put two layers of enkamat over the top of the stock two row needlewheel impeller. It doesn't seem to be necessary or perhaps even beneficial to remove the arms off of the impeller.

Then I removed the stock volute/venturi contraption that came with the pump and replaced it with a standard 1" PVC slipxslip coupler. One end of the coupler goes over the threaded inlet on the pump which can be sealed with about a dozen or so wraps of threadtape to provide a snug fit. In the other end of the coupler I inserted a 3/4" reducing bushing. Into the bushing I tapped in hole to install a Watts 1/4" quick connect fitting through the wall of both the coupler and the reducing adapter, about 1/4" from the end of the coupler. Last I installed an 3/16" wide ring of schedule 40 3/4" PVC to restrict the inlet a bit.

Things still to do to reach 14-15 LPM target:

- Round the transition outlet in impeller housing
- Grind out the stock outlet adaptor
- Add a 3rd layer of Enkamat to the impellor

[in_flight]

where is tbe cheapest place to pick up an octopus skimmer?

[ppurcell]

You can get them from:

www.octopusskimmer.com
http://www.aquacave.com/searchresult...CategoryID=222

not sure if this is there are any less expensive on-line shops to get them from, particularly since you are in Toronto.

[surfjeepzx]

After looking at Roland's venturi mod and how he made a 90 inside the coupling that gave me an idea. You can get vacuum T fittings of various sizes and configurations at the autoparts store. They're designed for automotive use within the various vacuum lines under the hood. I bought a box of assorted T's from autozone that have some L shaped or 90's in the box.

I pulled one of the 90's out and tryed to size it up to some RO line I have. It works perfect. Both ends are barbed, it's white plastic and it would work perfectly for this venturi mod. When I mod my skimmer pump this weekend I already know that I will simply use a section of pipe extended from the pump inlet. I'll drill a whole and insert the L fitting up through the hole from inside the pipe. I'll use some silicone or plastic cement to seal it and simply slip the air hose on.

The section of the L fitting will be pointed in towards the pump.

I've already scouted some of that mesh material at the local craft shop to mod the pump. I don't know what it's called or the brand name as I just remember seeing it when I was getting some vinyl for another project. So check your local arts and craft stores as I'm sure they all carry the mesh in the needlepoint section of the store.

[in_flight]

Originally posted by ppurcell
You can get them from:

www.octopusskimmer.com
http://www.aquacave.com/searchresult...CategoryID=222

not sure if this is there are any less expensive on-line shops to get them from, particularly since you are in Toronto.

thanks

[jdoenumber2]

http://www.premiumaquatics.com/Merch...y_Code=Octopus
Thats where i got mine. Cheap and smooth transaction.

WE NEED MORE PICS FOR THIS THREAD!!!!!!!!

[ppurcell]

my camera is out of town at the moment, I can post some pics on Sunday.

[medic29]

okay, I need to ask a dumb question....what is the volute of this pump? Can someone describe where it is at. There is the venturi piece that I have modded; and I'm considering opening up where the water exits the pump some, then also boring out the 90 elbow after the pump before it enters the skimmer. I've heard many talk about this volute, but for the life of me cannot figure out where this is.

Any help would be appreciated.

[ppurcell]

I looked this up because I had a feeling that I had confused the volute for suction nozzle.

The volute is the portion of the pump where the water leaves the empeller housing. Where the water actually leaves the pump is called a discharge nozzle. I realized late yesterday that I had used the term volute when I think I should have said that I removed the suction nozzle/venturi in my post but it was too late to edit the it.

I guess technically it's the part that is inside the case, and on the OTP-3000 it is reported that you can get a 20% increase in air flow if you round out that opening. It is not clear if that is 20% increase over stock or over any current measurement. The improvement could range from +1 lpm to maybe as much as +3 lpm depending on the answer.

[medic29]

round out what opening? the opening where the water leaves the impeller housing? or where the water enters the area where the impeller is located. I'm just trying to be clear here. Pics would definitely help here as I'm a visual learner to be sure.

There is the venturi (the short grey piece that the air hose connects to. Then there is the piece that goes into the impeller housing that the venturi actually connects to. There is a plastic ring the holds the previous piece on the pump. Then there is the impeller in the impeller housing. On the top is the discharge nozzel where the 90 elbow connects the pump to the skimmer. I don't know the names for all of the parts, but if someone could explain exactly which part is talked about opening up.

I was originally thinking someone was talking about boring out the back side of the venturi where the air line enters, but leaving the front half of the venturi narrow, this would increase the water volocity through the venturi and with the increase in area around where the air enters would create more suction and thus draw more air.

I have the ability to cast additional venturi pieces and was thinking about making another piece that resembles the short venturi, but making the hole through the venturi smaller and increasing the air intake hole; again to increase the volocity of the water moving through the venturi and hopefully this would increase the amount of air pulled and also decrease the amount of water allowed into the skimmer.

Any thoughts???

[ppurcell]

Here is a pick of a little larger pump than we are working with, but it identifies what each of the parts are.

http://www.cheresources.com/centrifugalpumps3.shtml

I'd take some pictures for you, but I can't do it until sometime tomorrow afternoon. Somewhere back in this thread someone posted some pictures on an easy venturi mod (which is the grey piece with the black threaded retention ring) by simply drilling a hole through it and inserting a 1/4" ice maker tube in it. This works fine, as you can easily test it by removing the grey venturi piece from the pump and just shove a length of tubing down into the pump intake. When the pump is in operation it sucks water into it. That suction will pull air through the tube and into the pump. Most of the threads I've read agree that you do not need a high performance venturi for needlewheel, meshwheel or threadwheel type pumps because you are only trying to get a lot of air to the housing so that the impeller can chop it up and push it into the reactor chamber.

You can accomplish this any number of ways, but the way I did it is easy, cheap and still looks pretty good without requiring any special tools (the threadtap is nice but not strictly necessary) and doesn't take much more space than the original venturi.

You can see some pics at the beginning of this thread before it was split on how to round out the volute opening:
http://reefcentral.com/forums/showth...5&pagenumber=4

[medic29]

Okay, that is what I was wondering. It is mainly trying to decrease the resistance to the water when exiting the pump, thus decreasing the back pressure.

[Papajin]

Originally posted by ppurcell
I looked this up because I had a feeling that I had confused the volute for suction nozzle.

I confused what I was talking about in my above post too. I was talking about the venturi, not the volute.

The parts that actually deliver the air into the pump should be inspected because I found mine were partially blocked.

[anin]

Hey all, I have the dnw 110 and I just ordered some enkamat and was wondering what is the best way to do it to the otp1000 pump? I mean as in, should i cut any of the needles or pins off? Also how many layers works best? I also planned on doing Roland's idea on reverse drilling the air line hole to fit a RO gusset fitting, what do you guys thinK? Ofcourse i run mine externally so it needs to be sealed,which it shoud be 100%

[JCTewks]

anin: just pop off onew of the NW's and sew 2-3 layers of mesh n with fishing line. that way, if you ever want to go back you can just put the NW back on.

[anin]

JCTewks: When you say pop off, u need to break it off or can you pry one of NW off? Thanks