[Delphinus]

No, luckily not. Basically it can only create a localized section of pressure differential and not really very much at that. So the water is still flowing through but the beckett can only suck in so much air. The skimmer drain will still be open so that will prevent the pressure from buildup up too high.

Tim, on a beckett skimmer the valves on the output is just to help adjust where you want your water/foam interface in the reaction tube. Depending on the pump you use, how high your skimmer is in relation to the water your pumping out of, and so on, you need to fine-tune this. The foam production can be a little finicky, i.e., if you feed the tank or even so much as put your hand in the water for a minute, the oils will disrupt the foam production and it can take as long as a few hours to start producing foam again. So because of this it's easy to overset the foam, then you come back in a few hours and the skimmer is spewing water all over the place. If you have an auto-shutoff collector then at least you haven't drained your tank.

With that said I don't run waste collectors on my two beckett skimmers, so I don't think it's a necessity (just a luxury). One day I might see about changing that but it will depend on budget and stuff like that.

The advantage of a setup like yours is simplicity, and efficiency (a downdraft airstone driven skimmer can be the most efficient skimmer you can get). The disadvantages are 1) you need a steady supply of woodstones because they only last for a few weeks 2) air pumps only last a year or so before they start to get finicky (unless you use a piston driven pump or whatever) and 3) particularly for large tanks, the size of skimmer that you need to maintain efficiency (in terms of height and diameter) can start to get a little ... large. A beckett skimmer on the other hand might be able to be fit into your stand.