Octopus DNW-200 Mod Questions

[davidabrown66]

Anyone out there have an Octopus DNW-200 that can share their experiences with doing the mods here:

http://www.reefcentral.com/forums/showthread.php?threadid=1053688 and here:
http://www.reefcentral.com/forums/showthread.php?s=&threadid=898776

Here's what I've posted on reefcentral, and I'm hoping there's some info from others here.

Ok, I finally got through reading the first forty pages and the last 17 pages of the split thread, but I still need some advice from people who have modded their DNW-200/RPS-3000. I'm hesitant about modding this, and it seems like most of the modding done has been on other models so I don't want to follow the same directions for modding this b/c they're different enough.

So far, this is what I've done:

I've done the gasket mod, and added 2 layers of Enkmat on my stock impeller attached with 10 lb fishing line. I've reamed out both sides of the venturi, and kept the original (long) venturi valve intact. It still has a 90 degree bend, but it now has a 1/4" ID diameter which is the same ID of RO tubing, unless we're talking 3/8" I guess. I saw an increase in bubble density when I added the 2nd layer, and reamed out the venturi, but that seemed to only last an hour or two. So, I'm not sure if a larger hole is the way to go, b/c it seems like there's a ratio that needs to be maintained.

I'm still not getting much foam, in fact my EV-180 took out a 1/2 cup daily, and this has only produced that much in 1 month. I know there's some break-in time, and I didn't prewash with vinegar, but I know there's stuff to skim b/c my nitrate shot up to almost 2.0!

I've only had it a month or so, and I have fine micro bubbles down to where the water re-enters the recirc pump. The water level is at the top of the 8" opening just before it tapers to the union. The foam collected is about 1/4" on top of that. It's been better, but I just added 150 ft total of plumbing to move my sump to the garage, so I know that'll kick it off for awhile, but even before I moved it, I was only getting about what I stated before.

Here are some questions I have:

1) I'd like to test a larger venturi hole, and I'd like to test this on a 1" pvc fitting with a 3/8" OD hole, but not sure if I should drill at an angle or keep the 90 deg turn in the venturi hole, and how to reconnect the pvc fittings again to the pump and body. Anyone done this on a recirc that can give me exact drilling sizes, pvc fittings to buy? I have threaded JG fittings for 3/8" OD if that helps.

2) I'm leary of trying to do any work on the volute or the pump housing to increase diameter, b/c I know it's easy to over heat the plastic, and I only have a drill. I have a 5/8" spade bit and a 3/4" sanding drum (as recommended by another DIY'r), but how do you ream it out if you can't put the tip of the bit on anything?

3) Do I need to give this some more gear time?

4) Is it recommended I buy another pump and/or Kilawatt meter before doing any other mods?

5) Is there another pump that works nearly as well as this one, but doesn't need any modifying?

6) I don't know what my air draw is yet. Is there someone local in the Puget Sound area that sells Dwyer meters? I'm looking to borrow or buy a RMA-7 (5-50) to use.

7)Do I need to ream out these parts I stated above in order to see a benefit in a larger venturi long term?

8) Am I missing something?

I'd like to hear the air being drawn into the ventui tube like a jet engine like someone else wrote, but I'm affraid I have to get my ear pretty close just to hear a girgly noise.

Any help would be much appreciated. If you're local and can lend a hand on the finer points, I'll pay for beer and pizza. Oh, did I mention I use to be a bartender

Thanks all!

 

[Fishead77]

octolpus skimmer

I have the nw150. Love it, never done the mesh mid as it works great with the needlewheel. I did get tired of emptying the cup. Drilled a 1/8th" hole in the top for airhose hooked to an aqualifter that runs on a timer 1 minute a day. This emptys into a one gallon jug that has to be emptied every few weeks. I have the skimmer set on the wet side for several reasons. One is it keeps the aqualifter from clogging up.

 

[davidabrown66]

I have the nw150. Love it, never done the mesh mid as it works great with the needlewheel. I did get tired of emptying the cup. Drilled a 1/8th" hole in the top for airhose hooked to an aqualifter that runs on a timer 1 minute a day. This emptys into a one gallon jug that has to be emptied every few weeks. I have the skimmer set on the wet side for several reasons. One is it keeps the aqualifter from clogging up.

Ya, the recirc's have a drain in the cup, so that was a nice improvement. To tell you the truth, I never ran it right out of the box. I spent $400, and as soon as it arrived, I had a drill in hand. I think it was b/c I'd read the 57 pages of that split thread above, and I was frothing at the mouth after reading all the people having success at modding these into performing like $2000 skimmers. It was a like a infomercial, and I couldn't wait to start. The DIY'rs go crazy over this skimmer, b/c it's relatively inexpensive knock-off that is easily modified to increase air/water flow = massive bubble density in the column which produces a lot more skimmate. I've done the basic mod's, and I've seen improvement with each mod even though I didn't have a baseline performance out of the box. I can tell that it's pulling more air now, but not sure how much, so I've ordered a Dwyer meter to measure.

How long have you had your skimmer? What size tank? How many fish? Do you get a dark skimmate or tea grean?

Thanks,

-David

 

[Fishead77]

How long have you had your skimmer? What size tank? How many fish? Do you get a dark skimmate or tea grean?
I've had the skimmer for almost a year now. I have a 90g with a 50g sump. Fish = 3 cardinals, 1 tang, 1 foxface, 1 copperband. I have about 100lbs LR. My skimmate is tea green as I have it set wet. I've seen the mods for the needlewheel/mesh, but haven't done anything. Using as is out of the box.

 

[davidabrown66]

Ok, good to know Fishhead77 - Thanks

I'm going to separate my return water from the rest of the sump and then have it flow into the sump so I can process raw water rather than just sump water.

For anyone out there using the recirc design, how many gal/hr are you using to feed your skimmer?

 

[Fishead77]

Ok, good to know Fishhead77 - Thanks

I'm going to separate my return water from the rest of the sump and then have it flow into the sump so I can process raw water rather than just sump water.

For anyone out there using the recirc design, how many gal/hr are you using to feed your skimmer?

By return water do you mean the water coming out of the skimmer? How will seperate it. As far as flow to the sump, I have a double cpr hob overflow with a mag 9 in the sump. The mag 9 has a 24" head pressure. I'd like to upgrade to a mag 12 since my overflow can handle more. I'm trying to get as much flow as I can through my sump. Do you have a drilled tank? I've heard these have no problems with getting lots of flow through the sump.

 

[davidabrown66]

By return water, I meant water coming from the tank, and having it flow to an area of the sump that is separated from the main part of the sump. This area will still flow into the main part of the sump, but I'll have a powerhead in that area to move raw/unprocessed tank water directly to the external skimmer. Then the water returning from the skimmer will reenter the sump at the opposite end where the pump returns water to the main tank.

I have a drilled tank with two closed loops (one under the rockwork, and one delivering water to a manifold at the top of the tank that has 6 outputs with loc-lines. Each pump pushes about 3000-4000 gal/hr, and my return is about 1300 gal/hr. CL's are great b/c you increase the flow of your tank without having all that water going through your sump. You really only need about 8-10 times your tank volume going through your sump.

Personally I'd never go with hob overflows again. Too much of a risk of breaking the siphon, and it's not a question of if, but when this is going to happen. I would also never max out my overflows. As an example, I have two overflows, and each one is drilled for a 1 1/2 return, so one can become completely blocked and still function.

Do you have an acrylic tank that can be drilled for bulkheads in the back? This would help you a lot in terms of making your own overflows and building a closed loop for circulation. It would also get rid of any unsightly powerheads that you might be currently using.

Are planning on keeping SPS? You'll want a tank turnover rate of at least 25x's per hour, and 30-40 x's per/hr being more the norm, but again not through the sump.

One of the biggest mistakes we make in this hobby is not giving our animals enough water movement. We can't even come close to what they get in the wild (millions of gallons of water moving throught the reef). This leads to poor health, cyano blooms, low o2 levels, organic build up, among other things, and eventually unexplained deaths, and a total tank crash.

What size tank do you have?

By return water do you mean the water coming out of the skimmer? How will seperate it. As far as flow to the sump, I have a double cpr hob overflow with a mag 9 in the sump. The mag 9 has a 24" head pressure. I'd like to upgrade to a mag 12 since my overflow can handle more. I'm trying to get as much flow as I can through my sump. Do you have a drilled tank? I've heard these have no problems with getting lots of flow through the sump.

 

[davidabrown66]

Oh, I see the size now...sorry I didn't see it at first. A mag 9 is probably enough for just a return if you have a lot more circulation in other areas.