<a href=showthread.php?s=&postid=12458745#post12458745 target=_blank>Originally posted</a> by cweder
What I find happening with this skimmer is that it skims great if I set it to have the bubbles breaking in the first couple inches of the neck, but it does not seem to have enough air to push the skimmate out and over the top of the neck and I get very thick, very dry skimmate with alot of mud to clean out of the neck every few days (not a bad thing), but not ideal. This is why, I believe, many find they have the bubbles breaking near the top few inches of the neck to get the foam out of the Orca 250 but I find operating it this way less productive for unknown reasons, which may be why people have gone to extending the neck another 5- 6 inches, but I found this to just give me dry skimmate again. Hope you can make sense of that Hahn.
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Okay, when someone tells me this, it makes me think of one of two things. This isnt set in stone however, and without seeing it in person, all I can do is speculate, however, if your bubbles are breaking as soon as they reach the neck rather than making a nice foam head, that means that there just isnt a whole lot of stuff in the water to skim out, or that the skimmer is hindered in some way which is preventing the bubbles from gathering enough of it to form a stable head. Either that, or your water level is just set too low. Perhaps a picture is in order, or better yet, a video.
Your tank, although a 450 w/ 30 fish (what TYPES of fish matters... 30 chromis or 30 large tangs, not to mention how often you feed), is mature. Mature tanks have a tendency to drop off in skimmate production. Simply put, the corals are all filtering the water for food, having grown in, and the bacteria have set up shop at that point to be at peak efficiency. Sometimes adding a larger skimmer doesnt mean you are going to get more out... sometimes a more efficient skimmer (smaller, yet can remove more of whats in the water) is the other way. You could see what happens if you try 'stripping' the water for a week... dose 20-30ml of everclear per day for about a week and see if your skimmate production doesnt spike (then stop... you go too far with it and you can easily overskim).
Otherwise, it could be the skimmer. Sometimes all that water fow and turbulence does nothing more than prevent the bubbles from attracting enough on their surface to form a stable head. Making the skimmer taller is one way to extend this contact time and reduce turvbulence, but there are other ways. Its alot like blowing bubbles... if you blow too hard, the film just pops... if there isnt enough soap in the water, the film pops on its own. If a skimmer is too turbulent, all that air could just be spinning wheels. It reminds me of a guy at the zeovit forums and here... gqjeff... he has a large well established tank, and his bubbleking just stopped working after years and years. It just couldnt keep up a stable foam head. Then he tried a KZ revolution, and although he first chalked it up to the cone shape and injection method, after some time I think he also realized that maybe part of it also had to do with the KZ being about 1/4 the air intake and 1/4 the size of the Bubbleking... simply put, as his large tank got older and older, there was less and less left for the skimmer.
In which case... start feeding more... alot more. Skunk that thing up and make your corals extend for food and your fish fatter than Boss-Hog. Chances are your corals are large colonies by now and could use more, and so could the fish.
The ethanol thing is a pretty good way to see if its your skimmer or the tank. If you try to strip it, and nothing improves (it should make 2x as much skimmate and much darker), then your tank just doenst make enough. The ethanol dosing boosts the carbon on hand so that a bacteria bloom takes place, and these bacteria absorb organics in the water, often ones that arent skimmable... but, the bacteria are skimmable. A side effect is that this bacterial plankton is also food for small mouth SPS (montis for instance), which cant feed on larger plankton. Check the vodka/ethanol dosing threads for more info on these methods. but yeah... you CAN overskim a tank. Its when your skimmer strips the water to either the point that the skimmer cant skim anymore, or the corals start starving.
