# Floating surface skimmer for HOB



## Sugardaddy1979 (Jan 16, 2012)

Gulfstream Tropical AGU00522 Ista Surface Skimmer for Aquarium:Amazonet Supplies

It's a great idea!


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## lochaber (Jan 23, 2012)

I've seen surface skimmer attachments that people use with cannister filters.

It may take some more work finding/adjusting fittings, but I don't see why one of them wouldn't work with a HOB intake just as well.


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## thinBear (Dec 16, 2011)

hmm... every time when water level changed (evaporation, wc...etc), most surface skimmer need to re-adjust the level of water intake in order to maximize/continue the skimming effect. And my original idea was using the floating material to auto adjust the level. Maybe my diagram doesn't illustrate well.

Today I finally have some time to test it out, and I realized the mechanism failed 
To maintain the water intake level that maximize the skimming effect , it must rely on support attached form the tank wall. When the water intake is a bit too low, water will flood the unit thus lost the skimming effect; raise the level slightly too much, the whole unit floats up and the HOB start sucking air. It is impossible to balance by using only the weight and the floating material.









When losing the support, the flow kinda work, but it lost most of the skimming effect already.








Fail. :icon_mrgr)"

ps: idea borrow from this


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## Idrankwhat (Mar 20, 2013)

Several companies make then for HOB filters. They're around $10 bucks. Almost worth using one that's produced than DIY when it's that cheap.


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## gSTiTcH (Feb 21, 2013)

I'm a fan of the cheap sucker that I got from Big Als Online, myself. Seems to be able to handle a wide range of water level fluctuations, and is highly adjustable to various filter flow rates.


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## evilhorde (Feb 3, 2012)

1. Find a tall glass tube (tall glass vase maybe?) that is as tall as your tank water height (bottom glass to desired water height) and maybe 2-3" diameter.
2. sink it in the tank and put your pick-up tube (from the HOB) into it.
3. fill the tank until it fills up the new glass tube.
4. turn on the HOB.
5. Monitor the level in the tube. When thet tube gets half empty, top it up. If the glass proves too light, put heavy stuff in it.

As a bonus, the water level in your tank will be very stable as only the level in the tube (vase) fluctuates.


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## GraphicGr8s (Apr 4, 2011)

Maybe I'm not getting this. 
Why can't you just cut a length of PVC pipe and cap one end. In the other end put 1" (approx) slits down the pipe. Attach to tank with suction cups. Put intake of HOB (or any other filter) into the top of the pipe. So long as the water level is above the bottom of the slits it's skimming. Isn't it? As I see it no need for floating devices at all.


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## Idrankwhat (Mar 20, 2013)

GraphicGr8s said:


> Maybe I'm not getting this.
> Why can't you just cut a length of PVC pipe and cap one end. In the other end put 1" (approx) slits down the pipe. Attach to tank with suction cups. Put intake of HOB (or any other filter) into the top of the pipe. So long as the water level is above the bottom of the slits it's skimming. Isn't it? As I see it no need for floating devices at all.


GraphicGr8s, I'll be in your neck of the woods next week. Any places over there I need to check out?


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## gSTiTcH (Feb 21, 2013)

GraphicGr8s said:


> So long as the water level is above the bottom of the slits it's skimming. Isn't it? As I see it no need for floating devices at all.


Not exactly. If the water level is too high, you end up pulling water from under the surface and not drawing down the crap ON the surface.


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## GraphicGr8s (Apr 4, 2011)

gSTiTcH said:


> Not exactly. If the water level is too high, you end up pulling water from under the surface and not drawing down the crap ON the surface.


Explain how that could ever happen. The bottom of the pvc is capped. The top is slotted. Only water that could possibly enter has to be from the top of 1" of the water column and would include the surface. Even if the water were to be above the slits it will still draw from the surface. In fact it will wind up creating a vortex.

Idrankwhat, sure. Check out Marine Warehouse Aquarium on Hillsborough. Creature Castle in Valrico on 60. Lakeland is Nolans Aquarium Superstore.


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## Idrankwhat (Mar 20, 2013)

GraphicGr8s said:


> .
> 
> Idrankwhat, sure. Check out Marine Warehouse Aquarium on Hillsborough. Creature Castle in Valrico on 60. Lakeland is Nolans Aquarium Superstore.


awesome thanks!


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## thinBear (Dec 16, 2011)

*gSTiTcH *means this.


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## GraphicGr8s (Apr 4, 2011)

Thinbear, if that drawing depicted what is happening than all the overflow boxes wouldn't skim the surface either. My pump keeps the water level about 3/4 of the way up the slits on the overflow. You telling me I'm not skimming because the bottom of the slit is an inch below the water level?


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## thinBear (Dec 16, 2011)

GraphicGr8s said:


> Thinbear, if that drawing depicted what is happening than all the overflow boxes wouldn't skim the surface either. My pump keeps the water level about 3/4 of the way up the slits on the overflow. You telling me I'm not skimming because the bottom of the slit is an inch below the water level?


I guess if the pump has enough power to "pull down" / "tear down" the surface of water, the surface skimmer is doing its job; but usually HOB don't have a very strong suction, thus the water intake need to be place very close to the surface.

To be frank I don't own a surface skimmer yet, one purpose of this simple experiment is to help me understand "how stuff works" better.


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## evilhorde (Feb 3, 2012)

GraphicGr8s said:


> You telling me I'm not skimming because the bottom of the slit is an inch below the water level?


You are certainly not skimming to the maximum potential of the weir (or whatever you want to call that grill in this instance).

However, that is in no way saying that you aren't skimming enough.
Thinbear's pic is a great example of what I mean. if you consider the 'hollow' spots on each. One is mostly skim, maybe 80% of the total volume is 'skim'.
The other is mostly water and only maybe 5% skim.
Perhaps a tank only needs 2% skim. In that case your grill is beyond appropriate however it is not performing as good as it could. The best skimmer would be a weir as long as possible with a waterfall as thin as possible. probably not feasible with animals in the tank, but certainly the most effective at skimming. the grill has two negative effects on the skimming abilty of the weir. By adding the vertical bars you use up half of the length of the weir and then you cause the water to back up and make the crest of the waterfall too thick, which is the opposite of what you want to accomplish.

However fish have issues with a nice smooth weir. The water is always clearer on the other side it seems that they just can't resist the temptation.


The skimmer I described further up is almost exactly what thinbear drew and works brilliantly. I haven't tried it in a fish tank (and do harbour concerns about fish jumping in) but I have used it to skim in other applications and using a 500ml beaker I had great success.

And just for a quick credential, my weir skimmer knowledge is from training I have received in watewater management.


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## AquticAsh (Jun 9, 2015)

This image describes exactly the problem I face with my skimmer. Unless its adjusted perfectly the water pulls from below the surface. Its pumping plenty of water but the surface tension never breaks and anything floating on the surface stays on the surface. The floating (self adjusting) system holds a lot of promise if done right. But anything else needs to be adjusted by millimeters to get perfect skimming. I have a standing pipe in mine and has to be adjusted when eveparation drops the water level by a millimeter.


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