Octopus Skimmer Mods

[jbeltmann]

For a venturi mod would simply taking a drill bit and boring the stock hole out a little bit work or would you have to drill a new hole for bigger tubing? Wasn't sure how much was needed to be effective. Forgot to mention I have a nw 150.

[davidabrown66]

To increase the air means doing a combination of:

1) Mesh - 2 to 3 layers
2) Reaming the input/output plumbing with 5/8" spade bit (not the venturi though)
3) Opening up the venturi airway 90 to at least 1/8". Opening up the airway more than 1/4" doesn't seem to move more air, or at least doesn't increase the air to water ratio IMO.

There are other mods as well as the ones mentioned above at the beginning of this thread. I'd recommend looking them over first before doing anything to yours.

[jbeltmann]

Just did the mesh today and man what an improvement. I stepped away for 30 min and the cup overflowed! Don't recall seeing the reaming input and outputs but I will reread again.

[squin]

Originally posted by davidabrown66
I went to customaquatics.com, and they have Spears metric fittings that I ordered a month or so ago. They only fit some of the pieces I need, and are too small for the skimmer unions, but do work for the input of the OTP-3000. From those parts, I found the corresponding part #'s on the spearsmfg.com website, and looked at the other model numbers that would hopefully work for the skimmer unions which would be one size up from what I had originally, and then I called in an order to customaquatics who would then order them for me and add them to my gen-x order and ship at the same time. The downside is I have to wait about 2 weeks for delivery, and there's still a chance that the fittings I ordered won't work, but i'm hopefull that between the new fittings and an old venturi I can put together the plumbing needed for the gen-x

Any concerns about the GenX rusting, or is that only a concern for the in sump skimmers?

[humbugy]

on my external dnw 200, i butchered the original paddle impeller, remmed out the output, trimmed the volute a little, 3 layers of mesh, modified venturi, and i pull about 15 lpm

[skwirl]

can somebody post me a parts list with pics to show me exactly what i need for a diy venturi for an octo 3000? they sent me the wrong pumps(i have 2 of em) ohh and what size drill bit do i need?

[davidabrown66]

Originally posted by squin
Any concerns about the GenX rusting, or is that only a concern for the in sump skimmers?

Only for in sump skimmers apparently.

As a side note, I bought a small propane torch yesterday and was able to heat up the threads on a standard 1 1/4 coupler and thread it onto a metric fitting. I let it cool for 5 min, and the I was able to take it off and re-thread no problem.

[davidabrown66]

Originally posted by humbugy
on my external dnw 200, i butchered the original paddle impeller, remmed out the output, trimmed the volute a little, 3 layers of mesh, modified venturi, and i pull about 15 lpm

You should be able to get about 20 SCFH with a little more volute work, and take a 5/8" spade bit and measure the ID of all your plumbing to make sure there's no bottle necks from input to output. That means the pump itself and the 90 degree restrictive elbow on the output. The only exception being the venturi. On the venturi drill the airway to 1/8" at both ends of the 90 to start with if you haven't already, and retain the original nipple for the venturi. Also, depending on the thickness of your enkamat, you might be able to go to 4 layers like I did.

It sounds like you're on your way to a better skimmer. If you want to pull more than 20 SCFH on these newer models, then you'll have to change pumps probably, and that's what I'm in the process of doing

[davidabrown66]

Originally posted by skwirl
can somebody post me a parts list with pics to show me exactly what i need for a diy venturi for an octo 3000? they sent me the wrong pumps(i have 2 of em) ohh and what size drill bit do i need?

Not that simple, and very good info you'll miss by not looking at the start of this post and reading up until now. There are at least 3 different ways people have had success with just the airway being opened up not to mention using a JG fitting or retaining the original nipple and reaming. If you just want to drill the venturi and retain the nipple I would use a 1/8" bit to start with, and drill both sides of the 90 in the airway without going into the waterway. This is the simplest way, but if you plan on doing more than that I would suggest reading the previous postings in this thread. I still scroll through it to get information from time to time.

Some othe the mods are easy to start with to gain some confidence, and will give you an instant performance gain. I would start by also buying a air flow meter here:

http://www.dwyer-inst.com/htdocs/flow/SeriesRMPrice.cfm

Buy the RMA-7, this will give you the necessary readings as you start to do the mods. Listening for airflow differences isn't enough, you need this.

Also, I would suggest buying a kill-o-watt meter b/c doing some of the mods incorrectly can cause a big jump in energy consumption, and knowing this will allow you to make some changes to you implementation, but this isn't as important as the air meter.

I and I'm sure others will help you along the way with any questions you have.

-David

[Bunkerbean]

So I ordered my RMA7 are there some fitting I need to get to be able to measure the airflow?

[davidabrown66]

Originally posted by Bunkerbean
So I ordered my RMA7 are there some fitting I need to get to be able to measure the airflow?

You could, but I didn't at first. If you're using the stock airline that comes with the DNW-200 for instance I think it's 3/16", it fits just inside the female threaded hole inside the unit, and it measure accurately, but you have to hold it there. I've since bored my venturi out to 3/8" and use the same barbed fitting on the rma-7 which threads perfectly. Not sure where you would buy the fittings if needed them. Also, if you're using ro/di line, then that line would fit perfectly inside the 3/8" barbed fitting that you could use on the flow meter as well so I think you're covered.

[Bunkerbean]

Unfortunately I have the 150 so it is still the small plastic clear hose. Do you have a picture of you setup?

[davidabrown66]

Originally posted by Bunkerbean
Unfortunately I have the 150 so it is still the small plastic clear hose. Do you have a picture of you setup?

Ohhh, you have the nw150 on a 300 gal!!? You're going to need everything that that skimmer can do. Do you have the OTP-2000 then?

I don't have pictures yet, I really need to do that going forward. Everything I've done so far has been documented and posted with pics from others on this thread, but now I'm getting into uncharted waters now that I'm changing the external plumbing and pump for my recirc.

I'm not sure what size OD the hose is that comes with your skimmer, but if I were you, I'd wait until it arrives and then go to an ace or mcclendons hw store and pick up a barbed fitting that is threaded for 3/8" with the other end being whatever your hose is. Forget about HD having these, and even Lowes won't carry a very large selection. You need a true hw store, not a home improvement store to find the best selection of watts fittings.

[Bunkerbean]

No the 300 gallon is long gone. It is on a 125 gallon. So yeah it is the 2000.

So drill out the 90 degree hole to 3/8"? I do have RO line I can use.

I have a True Value Hardware store in town.

[humbugy]

15 lpm is about 31scfh

Originally posted by davidabrown66
You should be able to get about 20 SCFH with a little more volute work, and take a 5/8" spade bit and measure the ID of all your plumbing to make sure there's no bottle necks from input to output. That means the pump itself and the 90 degree restrictive elbow on the output. The only exception being the venturi. On the venturi drill the airway to 1/8" at both ends of the 90 to start with if you haven't already, and retain the original nipple for the venturi. Also, depending on the thickness of your enkamat, you might be able to go to 4 layers like I did.

It sounds like you're on your way to a better skimmer. If you want to pull more than 20 SCFH on these newer models, then you'll have to change pumps probably, and that's what I'm in the process of doing

[davidabrown66]

Originally posted by Bunkerbean
No the 300 gallon is long gone. It is on a 125 gallon. So yeah it is the 2000.

So drill out the 90 degree hole to 3/8"? I do have RO line I can use.

I have a True Value Hardware store in town.

I would take the stock SCFH air draw first, and make small adjustments and retest with air meter. For example, I would try a smaller ID of 1/8" and retain your 90 bend in the airway and ream out the venturi nipple where the airline attaches first. Don't drill all the way through to the waterway for right now, and check for blockages of shavings in the airway to make sure you have it cleared. I would put your venturi in a vise, and measure the depth of the airway with your 1/8" drill bit, and wrap electrical tape around the area of the drill bit that you don't want to enter the hole you're drilling. Make sure the drill is going straight in to the venturi hole for both ends. Retake air measurements. Add one or two layers of enkamat and retake air measurements, and add a third layer, etc. I don't know how much the OTP-2000 differs from the OTP-3000, but I know that mods work on both, but the drill measurements will have to be adjusted accordingly, and that's why I said 1/8" to start off with. You can go to 1/4" for the hole and insert RO line, but it's best if you discover what works best for your situation.

I would also make sure your plumbing is reamed out for your input/output plumbing to/from the pump, and look at what others have done to the volute which is area that houses the nw impeller.

I would also adjust your water level lower in the skimmer for 24-48 hours after doing any mod, b/c this thing will double in performance over night and flood your floor if your not carefull.

[Bunkerbean]

Well I kind of blew it. I moded the venturi before I got the AIrflow device. I have been watching this thread for a while. I just caught the device a little later. Whoops....

[davidabrown66]

Originally posted by Bunkerbean
Well I kind of blew it. I moded the venturi before I got the AIrflow device. I have been watching this thread for a while. I just caught the device a little later. Whoops....

No worries.

Can you give me some info on what you've done so far?

[Bunkerbean]

Mesh moded the NW with 2 layers. Drilled the nipple and 90 degree bend out on the venturi. That is it.

[davidabrown66]

Originally posted by humbugy
on my external dnw 200, i butchered the original paddle impeller, remmed out the output, trimmed the volute a little, 3 layers of mesh, modified venturi, and i pull about 15 lpm

Oops, misread thanks for the correction...WOW!...your skimmer is rockin!!!

You must be one of the fortunate ones that got into this before they changed the pump and nw a few months ago. It used to be that 30 to 40 SCFH was possible, but not anymore with the next generation of OTP-3000's. Congrats on your mods!

Can you tell I'm jealous?

To get that kind of performance going forward, there's going to be a need for changing the plumbing to standard instead of metric, and a pump swap. I just ordered a Gen-x 4100 with SP4 (euroreef nw, volute, and venturi), so I should be able to get around 1100 lph when I'm done.

[davidabrown66]

Originally posted by Bunkerbean
Mesh moded the NW with 2 layers. Drilled the nipple and 90 degree bend out on the venturi. That is it.

I would wait for your meter, and then see what the improvements bring, like can you go to 3 layers of PF4?

The volute grinding is important and an overlooked mod. You could get 2 - 3 SCFH more if you shave a little off to make the angle of the water leaving the pump a little easier path to take.

What size did you drill to on the airway? Did you retain the 90 in the airway, or did you drill all the way through to the waterway? I've done both, and didn't see an improvement in one vs the other, nor an improvement when I drilled out the venturi completely to 3/8". The enkamat, the plumbing, minor venturi reaming, and volute are the main things.

Check your input/output plumbing for bottle necks. The OTP-3000 is supposed to be 1" in and 3/4" out (metric equivilent that is), and at some point in the input/output there were areas that were less than 5/8" that could easily be reamed out with a spade bit to increase water flow...not sure what that would be on the OTP-2000.

[Bunkerbean]

I already have that too. I just have to get the fittings to insert the tubing.

I think the airway is like 3/16? I will have to check. I might be able to do 3.

What is the Volute?

[davidabrown66]

Originally posted by Bunkerbean
I already have that too. I just have to get the fittings to insert the tubing.

I think the airway is like 3/16? I will have to check. I might be able to do 3.

What is the Volute?

The volute it the part of the pump that the nw sits in. The grinding that I've seen and is pictured in this thread somewhere is where the water leaves the pump. You can grind the edges down so the water has an easier time leaving the pump which increases water throughput.

[davidabrown66]

Ah, I found it. The pics of before and after volute gringing here:

http://reefcentral.com/forums/showth...5&pagenumber=4

[Bunkerbean]

Your a stud!