Surface skimmer bouncing.

[Luciën]

Hello I have a surface skimmer on my filer intake. But sometimes it starts bouncing up and down causing it to suck in air to the filter.. Even if I turn open the bottom of the intake. I really have to cut down the flow of the filter for it to stay stable. Is this a common issue? Is my filter rating to high.. it is rated 1200l/h.

 

[Tim Harrison]

I could never get mine to work properly either, so I went back to normal lily pipes and bought a Eheim Pro Skim 350 instead.

 

[Oldguy]

surface skimmer on my filer intake. But sometimes it starts bouncing up and down

I just bought a small cheap surface skimmer with its own motor. Run it as and when required. It too has a tendency to bounce and suck air in. Found the flow rate through the unit to be very critical. In the end fastened the float chamber to a set position with stainless steel wire and this stopped it bouncing.

 

[Andrew Butler]

Which kind of surface skimmer do you have? - I tried out a stainless steel one and I had to drill the holes out a little bigger in the end but it then worked perfectly.
The lily pipe that went with it had a very targeted jet which blew my soil to pieces so I stopped using it and am waiting on my glass one to arrive.
Many people seem to get the glass ones working okay so hopefully I can.
I did notice that George Farmer uses the 12mm ones instead of the 16mm ones even though the filter uses 16mm and he just reduces the pipe size; maybe this is the reason?

 

[Luciën]

This is the one.. I can drill the holes bigger if i wanted. But I dont know if it going to look better, I keep it as an future option.
For now I lowered my cannister flow..It sure is fiddly to get it to stay the same as the filter clogs up more during the end of the week..

i don't have problems with the flow of the outtake.. i have an extra small wave maker next to it and I'm thinking about an other wavemaker for in the lower regions. The thick plant mass restricts a lot of flow..

Verstuurd vanaf mijn SM-J330FN met Tapatalk

 

[Siege]

Hi,

George uses 12mm glassware at the mo with 16mm filter simply because he broke his 16mm glassware and EA were out of stock so he reduced it.

Mine has bounced a couple of times. You can see in video below at just after 8:50. Prefilter was blocked by plant bits which reduced flow. Assuming you are using glassware I’d look at at the filter first. Give it a good clean. Clean hoses and make sure it is not packed with media reducing flow.

Just my experience.

Ps. Just saw your steel inlet. Yes, play with the filter then think about holes. Andrew Butler had the same issue with it I think. Might be worth sending him a message.

 

[Andrew Butler]

George uses 12mm glassware at the mo with 16mm filter simply because he broke his 16mm glassware and EA were out of stock so he reduced it

And there was me thinking there was a technical reason for it!

This is the one.. I can drill the holes bigger if i wanted. But I dont know if it going to look better, I keep it as an future option.

So you have a SS one which means you can drill the holes out slightly bigger if you need to.
Have you tried adjusting the piece inside that covers/uncovers the holes?

 

[Daveslaney]

I've used them in the past and had the same kind of issues with them too. One day it would be working fine. The next sucking air in. I just went back to using the eheim skimmer.

 

[Luciën]

It stopped bouncing now.. I noticed if the skimmer spins to much from the flow of the wave maker it has problem getting stable even if I stop it by hand and if there is just a bit to much leaves stuck to the underside the it is going to suck too much also and causes bouncing..
Don't think a 12mm is going to help as it seem more logical that the filter pulls the water even harder.
My only option looks like drilling larger holes just a little bit to have more room to play with the flow regulator on the bottom and keep it clean of course.

 

[Andrew Butler]

Don't think a 12mm is going to help as it seem more logical that the filter pulls the water even harder.
My only option looks like drilling larger holes just a little bit to have more room to play with the flow regulator on the bottom and keep it clean of course.

I know I kind of contradicted my suggestions here but as @Siege has already said the 12mm was simply as they had none in stock; I was unsure if there was some science behind it.
From personal experience I had to drill the holes slightly larger to make things work which isn't too hard to do.
I suggest using use sharp drill bits, drilling it in small increments and take the time to set it up so the drill bit's not sticking out too far out from the chuck and then add some tape, a piece of rubber or something similar to the front of the metal chuck jaws so when you have drilled through it shouldn't mark the SS pipe.

I've used them in the past and had the same kind of issues with them too. One day it would be working fine. The next sucking air in. I just went back to using the eheim skimmer.

This isn't what I want to hear! I had some SS ones working perfectly on my old Fluval G6 filters but I've since changed over to the Oase to get rid of the inline heater.
I've also ditched the SS ones as the lily pipes jetted my substrate everywhere due to the very targeted flow.
Maybe I've made a huge mistake!

 

[Siege]

Interestingly never had the problem on any oase 600, just on my 1 Eheim Pro 4 600 with me being lazy and not clearing out cuttings.

Hope it makes you feel better.....

 

[Azzaliah]

I put an O-ring on the skimmer and left it 0.5mm for maximum swing and that solved it. When it starts to sway, the ring stops it, because it can't go any further and the skimmer stabilizes again.

 

[zozo]

Even tho I never used one myself... I think I caught the idea behind it...

Looking at George's video and the way it is designed and constructed, the skimmer seems to be a floating and somewhat loose sliding fit and stays afloat because it's shaped like a cup and collects an air pocket beneath the skimmer weir. If you look closely his skimmer also bounces a little bit around with waves made with the surface agitation from the filter outlet. That's the whole idea behind it to keep the skimmer weir afloat at the surface.

With the design he bought, he can regulate the skimming capacity with that diagonal cut-off plug at the submerged filter inlet side. There the skimmer's suction needs to be synced with the pump capacity. If the pump sucks too much at the skimmer side it will pull it down and the air pockets buoyancy wants to push it back up. Since the sliding part is a tube inserted in another tube, like a piston in a cylinder, it needs to have some play and it wiggles with the surface agitation that causes some friction. This wiggling and friction in the up-and-down movement causes it to bounce erratically.

If such a design has no option to sync the turnover between the skimmer and the submerged inlet part it can be considered a small design flaw. With some limitations in filter turnover if you can't work out the bouncing your pump is too strong.

With the glass version, you can see that air bubbles are always sucked in with a skimmer, these bubbles collect in the filter. To prevent a noisy filter is again in the filter design and where the air collects... For a skimmer, a canister filter design like a type B filter in the drawing is best a type A filter will always be noisy at one time since the air in the filter always collects and stays at the top. In type A filter design gas and air can collect under and in the filter media, till it's a big enough pocket with enough buoyancy it will work its way through and a big gas air bubble will end up in the impeller housing making noise. Since it's a non-self priming pump it can stay a while...