View Full Version : Knop hang on skimmer

02/08/2000, 12:30 PM
I've been running a Knop on my 55 for over a year. With the original Rio pump, it was erratic and, while it never overflowed, it often produced wet foam and I had to watch it like a hawk.
I was ready to get another skimmer until I replaced the Rio with a Maxi-Jet 1200 with venturi kit (Premium Aquatics). It became a very different skimmer producing smaller bubbles and good dry foam. I've had no more problems and am now, at last, satisfied with it.
Can't say this is a cure all as some others have reported continuing problems after the upgrade but it works for me!

[This message has been edited by FishDaddy (edited 02-08-2000).]

02/08/2000, 01:20 PM
Here's an idea for a modification that could save you from getting a gunky floor when it overflows.
Drill a small "drain hole" in the bottom/side of the collection cup and run tubing to a larger collection cup under the tank. This is what the bigger skimmers (specifically the Reef Devil I have) do.
I just bought a Knop for a new tank and like it so far. I've heard from others that the Maxi-jet 1200 switch is a good idea also.

02/08/2000, 09:25 PM
I have the same problem with my knop.
I've tried it with the rio and the maxijet 1200 with the same results. The only thing that's worked for me was to put a tube thru the little hole in the lid of the cup, and let the other end of the tube fall right back into the tank. At least with this setup I don't have to worry about it. It's running with the rio now, but I think I'll give the maxijet another shot to see if it overflows more often.

See my tank at

02/08/2000, 10:27 PM
Targus, how does the small hose going back in the tank work? Wouldn't it have to keep a siphon to work properly? I just put the Venturi modification on just to have it overflow the first night it was up and running. I am thinking about making a drain hole somehow to keep from having to worry about it and to avoid the hassle of removing the collection cup. I have a real hard time removing it sometimes because the seal is so tight. Anyone with any input on this? Nathan

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02/08/2000, 10:36 PM
I have a KNOP hang on that I am going to add a drain hole to soon. If you've ever seen the drain hole on a Reef Devil, that's exactly what you want it to look like. Basically you need to drill a hole in the bottom-side of the collection cup; screw in a small plastic elbow thingy, (screw end into the cup with some teflon tape to seal it, slip end facing out to attach the tubing); run the tubing to a bigger container and BAM! no need to ever take off the collection cup. Well, maybe for a bi-annual cleaning... lol
Does any of that make sense?


Mushroom Boy
02/08/2000, 11:12 PM
How much do they overflow? I just bought one used and am now a little concerned. Also, is there something that's supposed to go on the o-ring of the collection cup to create a seal?

02/08/2000, 11:39 PM
I have a Knop skimmer on my 55 gallon. What can be done to modify this thing so it is easier to adjust. Just when you think it is all set, you go to work or to sleep and it overflows. I replaced my bacpak because it didn't skim good enough. This one skims great but I'm sick of playing with it. After every water change, or cleaning or whatever, it has to be adjusted. What can be done to make it where you set it and that's it besides a new skimmer. Should I put the bacpak back on? The bioload is big with 6 fish (about 15 inches) but they are full grown so it won't increase.

02/09/2000, 03:12 AM
i had my knop up and running since mid dec and it overflowed only once. the reason it did is because i put an additive in the water and it went to work fast. it's an excellent skimmer, but noisy,as most are. i use a modified skilter all the time, then when i see it start to pull foam, i put the knop to work. i made a small hole in the collection cup of the knop and ran an airline hose back to the tank. if it overflows, it will be mostly clean water back because i keep the cup clean.

02/09/2000, 09:29 AM
Hi Nathan,
All I did was put an air tube thru the little hole on the plastic lid of the cup about an inch down, and set the other end of the tube over the tank. When it starts to overflow, the tube causes the water to slow down and just drip into the tank.

See my tank at

02/09/2000, 04:42 PM

I put just a very small amount of silicon grease on the o-ring. It slips on and off really easy with the grease. Silicon grease is not harmful. You could also use KY. It is very non-toxic.

I am also going to put a drain line on my knop. I will be going on vacation and don't want the people that are feeding the tank to have to clean the skimmer.


He who feared he would not succeed sat still.

02/10/2000, 12:09 AM
I had a skimmer that was hard to get the cup off when it was new,so i put a layer of NovAqua on the cup shaft every time i removed it.Also found on that skimmer cup it was easier to take off by wiggeling it back and fourth,rather than trying to twist it off.There are probaly better ways,but it was 1st thing i thought of and it did help.