Wow it must have been a flashback or something
, I just realized that Tony had posted a reply to my question about this skimmer- what over two years ago
Tony Wrote:
Quote:
Since our conversation I've been thinking about this skimmer some.
Realistically all my comsplaints can be traced back to one design shortcoming: the reaction chamber is too small.
What happens for me (and others) is that you need to crank back the water volume to something like "5% open" in order to prevent the air/water foam from rising too high in the collection cup and spilling over into the cup with perfectly clean water as skimmate.
But the problem for me is that the water flow is so cranked back that air can get into the U-tube, and breaks the siphon within a matter of 12 hours or so. A skimmer is no good if it shuts itself down, no matter how good that foam is.
Thus, there are two modifications I will suggest for anyone who has a Prism and isn't 100% happy with it.
The first is the easy one. Put an airline valve on the air intake. Turn up the water volume, and slowly increase the air until you get some foam. Just don't overdo the air, or else you'll overwhelm that little reaction chamber. Here is the key. You need a top-quality air valve. Those plastic cheapy jobs aren't going to give a fine enough adjustment. What will happen is suddenly they allow too much air in as you slowly open them ... and then the fine adjustments are defeated and the skimmer overwhelms itself.
The only thing I don't really like about this idea is that any time you allow more water through the skimmer, the higher the water column will rise into the reaction chamber, thus giving you less volume in that chamber for good foam production.
This leads me into my second idea (which I haven't tried yet, because I'm going to give idea #1 a solid week or two to see how well it plays out long-term).
The problem is the reaction tube is too small. So, why not extend the reaction tube? It would just be a matter of finding a tube of the appropriate diameter, and you can place this "riser extender" between the skimmer and the collection cup. Perhaps a length of gravel vacuum tubing would work (I haven't looked into this yet). If I try this then I'll post some pictures in the DIY forum. But this way we could have the water AND air fully open. I figure that so long as the tube is long enough the contact time should be long enough and give a really high density skimmate. It wouldn't look too pretty but then again function is more important than esthetics the way I see it
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