Skimmer startup question

perseus · 10/09/2007, 05:25 PM

I have an Octopus recirc NW skimmer. I'm not sure what the model is but it has a OTP-2000 pump attached to it. I modded it with the mesh mod and boring out the volute slightly. It pulls about 7 L/min. It is gravity fed under my 90 gal tank.

My question is: I currently have to blow (pretty hard) to get it started into the venturi tube. Is this normal? Is there anything I can do to have it self-start?

JCTewks · 10/09/2007, 11:39 PM

if you trim down the diameter of the mesh slightly it will help. the air may go down some too though. I've found that it's better to have more layers pf a smaller diameter. I use a piece of gutter guard to hold the mesh down to keep it from rubbing the volute cover.

btw your skimmer is a DNW150

SlowCobra · 10/09/2007, 11:43 PM

And JCT left out the most important information.... NEVER MESH MOD THE PUMP WITHOUT HAVING A KILL A WATT METER!!!!

JCTewks · 10/09/2007, 11:45 PM

LOL thanks todd...i think i'm going to start calling you the killawatt cop

SlowCobra · 10/10/2007, 12:14 AM

I just hate seeing people that start with the:

"I did the mesh mod and fried my pump after only 3 months. 10 other people in my club had the same problem."

Then this information goes to people new to DIY and I feel that while there is some merit to it, the majority of the blame is those that try to perform the mods with the improper tools. This in turn scares anyway away from making their skimmers perform like monsters due to false information.

I was skeptical that I would ever use the kill a watt for anything more than modding my skimmer. Oh how wrong I was. It actually turns into quite the handy little tool. I know exactly what each piece of equipment is pulling for wattage. If I ever suspect a problem or something changes I can start testing and figure out which piece of equipment is causing the problem.

perseus · 10/10/2007, 07:30 AM

I do have a Kill a watt meter for testing. It never self-started to begin with, which is why I started mod-ing it. The water level in the air tube comes up to the water level in the skimmer when it is off. It barely drops an inch or so when the pump kicks on. Do you have a pic of the gutter guard? And is this skimmer even supposed to self start?

Thanks everyone!

DarG · 10/10/2007, 07:36 AM

I had two of the OTP 2000's that never would self start the air draw. Actually, they did once in a long while. Others here have said the same thing. It's normal, although I know that one person got it to self start by doing something ... I think he bored out the air holes on the venturi elbow but dont quote me, I'm not sure if that was what he did.

JCTewks · 10/10/2007, 10:44 PM

Here is a couple pics of an OTP3000 impeller with mesh and GG

Photo Sharing and Video Hosting at Photobucket

Here is an OTP1000 impeller with GG on top and bottom. Notice how thin the whole thing is. that is 4 layers of mesh and 2 of GG!

Here is my modded venturi from a DNW110

perseus · 10/12/2007, 12:39 PM

Disaster! I got the o-rings and they didn't fit. So I trimmed the existing plastic removable washer. That pushed my l/min almost up to 15. Well, I let the skimmer run overnight and it overflowed the collection 2L bottle I had. It also covered most of my carpet and ran down my building (I live on the 17th floor and it ran down 4 floors).

So far the water removal people have removed my water and the floors below only seem to be moist. Hopefully it will turn out alright. I've completely taken apart my tank to move it for the water guys. Everything survived and is in buckets for now.

Anyway, should I limit the flow into the skimmer since it just overflows with bubbles now and it isn't really skimming protein out? The outgoing valve was wide open.

JCTewks · 10/12/2007, 11:20 PM

you'll need to lower the "tee" on the output pipe. that much air will just do what it is doing...overflow. Just cut a little bit off (1" or so) and try it that way....if it's close still, cut some more off until you have some control with the valve. you should also measure your flow into the skimmer and make sure it is at 1-1.5x your system volume per hour. If it is more than that, slow it down until you are where it should be.

How much water did you lose? I put 5gal through the hardwood floors into the basement (old house

) when mine finally broke in after mods

DarG · 10/13/2007, 07:57 AM

I would lower the T more than an inch. With the Output valve, it reall doesnt need to be lowered in increments, you will always be able to raise the water height in the skimmer, no matter how low the T is, by closing off the valve. Lower it 2 or 3 inches below the start of the cone.

JCTewks · 10/14/2007, 12:04 AM

IME it's better to not have to close the valve as much. The valve works by putting back pressure in the skimemr, and if it ever gets clogged a little (like a piece of algea or something) it will overflow the skimmer pretty quickly. having the output at close to a proper level will allow the water to naturally drain without so much risk of flooding. IMO it's also easier to make fine adjustments if you are using the first "half" of adjustment with the ball valve instead of working with a nearly closed valve.

10/09/2007, 05:25 PM	#1
perseus Registered Member Join Date: Nov 2004 Location: South Florida Posts: 14	Skimmer startup question I have an Octopus recirc NW skimmer. I'm not sure what the model is but it has a OTP-2000 pump attached to it. I modded it with the mesh mod and boring out the volute slightly. It pulls about 7 L/min. It is gravity fed under my 90 gal tank. My question is: I currently have to blow (pretty hard) to get it started into the venturi tube. Is this normal? Is there anything I can do to have it self-start?

10/10/2007, 10:44 PM	#8
JCTewks Moved On Join Date: Oct 2005 Location: Wilmington, Ohio Posts: 3,040	Here is a couple pics of an OTP3000 impeller with mesh and GG Here is an OTP1000 impeller with GG on top and bottom. Notice how thin the whole thing is. that is 4 layers of mesh and 2 of GG! Here is my modded venturi from a DNW110

10/12/2007, 11:20 PM	#10
JCTewks Moved On Join Date: Oct 2005 Location: Wilmington, Ohio Posts: 3,040	you'll need to lower the "tee" on the output pipe. that much air will just do what it is doing...overflow. Just cut a little bit off (1" or so) and try it that way....if it's close still, cut some more off until you have some control with the valve. you should also measure your flow into the skimmer and make sure it is at 1-1.5x your system volume per hour. If it is more than that, slow it down until you are where it should be. How much water did you lose? I put 5gal through the hardwood floors into the basement (old house) when mine finally broke in after mods

10/09/2007, 11:39 PM	#2
JCTewks Moved On Join Date: Oct 2005 Location: Wilmington, Ohio Posts: 3,040	if you trim down the diameter of the mesh slightly it will help. the air may go down some too though. I've found that it's better to have more layers pf a smaller diameter. I use a piece of gutter guard to hold the mesh down to keep it from rubbing the volute cover. btw your skimmer is a DNW150

10/09/2007, 11:43 PM	#3
SlowCobra Registered Member Join Date: Mar 2007 Location: Joliet, IL Posts: 3,079	And JCT left out the most important information.... NEVER MESH MOD THE PUMP WITHOUT HAVING A KILL A WATT METER!!!!

10/09/2007, 11:45 PM	#4
JCTewks Moved On Join Date: Oct 2005 Location: Wilmington, Ohio Posts: 3,040	LOL thanks todd...i think i'm going to start calling you the killawatt cop

10/10/2007, 12:14 AM	#5
SlowCobra Registered Member Join Date: Mar 2007 Location: Joliet, IL Posts: 3,079	I just hate seeing people that start with the: "I did the mesh mod and fried my pump after only 3 months. 10 other people in my club had the same problem." Then this information goes to people new to DIY and I feel that while there is some merit to it, the majority of the blame is those that try to perform the mods with the improper tools. This in turn scares anyway away from making their skimmers perform like monsters due to false information. I was skeptical that I would ever use the kill a watt for anything more than modding my skimmer. Oh how wrong I was. It actually turns into quite the handy little tool. I know exactly what each piece of equipment is pulling for wattage. If I ever suspect a problem or something changes I can start testing and figure out which piece of equipment is causing the problem.

10/10/2007, 07:30 AM	#6
perseus Registered Member Join Date: Nov 2004 Location: South Florida Posts: 14	I do have a Kill a watt meter for testing. It never self-started to begin with, which is why I started mod-ing it. The water level in the air tube comes up to the water level in the skimmer when it is off. It barely drops an inch or so when the pump kicks on. Do you have a pic of the gutter guard? And is this skimmer even supposed to self start? Thanks everyone!

10/10/2007, 07:36 AM	#7
DarG Registered Member Join Date: Dec 2006 Posts: 5,515	I had two of the OTP 2000's that never would self start the air draw. Actually, they did once in a long while. Others here have said the same thing. It's normal, although I know that one person got it to self start by doing something ... I think he bored out the air holes on the venturi elbow but dont quote me, I'm not sure if that was what he did.

10/12/2007, 12:39 PM	#9
perseus Registered Member Join Date: Nov 2004 Location: South Florida Posts: 14	Disaster! I got the o-rings and they didn't fit. So I trimmed the existing plastic removable washer. That pushed my l/min almost up to 15. Well, I let the skimmer run overnight and it overflowed the collection 2L bottle I had. It also covered most of my carpet and ran down my building (I live on the 17th floor and it ran down 4 floors). So far the water removal people have removed my water and the floors below only seem to be moist. Hopefully it will turn out alright. I've completely taken apart my tank to move it for the water guys. Everything survived and is in buckets for now. Anyway, should I limit the flow into the skimmer since it just overflows with bubbles now and it isn't really skimming protein out? The outgoing valve was wide open.

10/13/2007, 07:57 AM	#11
DarG Registered Member Join Date: Dec 2006 Posts: 5,515	I would lower the T more than an inch. With the Output valve, it reall doesnt need to be lowered in increments, you will always be able to raise the water height in the skimmer, no matter how low the T is, by closing off the valve. Lower it 2 or 3 inches below the start of the cone.

10/14/2007, 12:04 AM	#12
JCTewks Moved On Join Date: Oct 2005 Location: Wilmington, Ohio Posts: 3,040	IME it's better to not have to close the valve as much. The valve works by putting back pressure in the skimemr, and if it ever gets clogged a little (like a piece of algea or something) it will overflow the skimmer pretty quickly. having the output at close to a proper level will allow the water to naturally drain without so much risk of flooding. IMO it's also easier to make fine adjustments if you are using the first "half" of adjustment with the ball valve instead of working with a nearly closed valve.