what does a skimmer do and how can you screw it up? FYI

[Sk8r]

Ever been to a beach when the waves have been pounding the shore? Froth. Froth everywhere.

That's the ocean's skimmer. Remember the pix from when children were playing in mountains of seafoam washing ashore this last year? Tank owners were appalled.

When water is charged with amino acids from protein breakdown, and you hit it with a garden hose, it will foam and froth. That foam and froth is the amino acid bit. "Skim" it off and throw it away and your water is cleaner for it.

That's what a skimmer does: a jet hits a reservoir of water, creates froth, bubbles rise and rise in a column, plop into a cup, reliquify as the froth piles deeper and surface tension on the bubbles breaks, and you get to dump the collection cup.

Many advanced skimmers have several adjustments, an air intake toggle, a water inflow adjustment, and a water outflow adjustment. "Tuning" a skimmer means to adjust these to get the best compromise between speed and not wasting water by having a very wet froth [containing a lot of water] plopping into collection.
"Skim wet" means run it with wet froth and get whatever it is out of your tank fast, but when you are skimming 'wet' you need to monitor your salinity: it will be pulling water out and your autotopoff will be pouring fresh water in.
"Skimmate" is, of course, the crud in the collection cup. You want it to be as dark as possible, indicating a) a good job and b) it's not disturbing your water/salt balance.

How big a skimmer should you buy? I say, me, one 2x the rating for your water. I have a 54g tank and an EV 120 skimmer: my previous one wasn't doing it for me. There are several technologies, but the end result is the same: this machine is the 'kidneys' of your tank, part of its waste disposal system, and it is way important to keep it operating at optimum.

What screws up a skimmer? Number one---oil. Anything oily. Your hands. Especially, women, your hands after using hand lotion. Or moisturizing soap. You name it. Read the label: if it says oil, it is going to foul up your skimmer. Skimmers come, sometimes, with a protective oil coating from manufacture: wipe a new skimmer down with vinegar: seems to help.
Foods contain oil. Fish oil. Etc. If you stick your hand in the tank, your natural skin oils will stop it skimming for the better part of an hour. Feeding will do the same thing. Any oily contaminant will take longer than that. If you are trying to 'tune' your skimmer and keep sticking your ungloved hands in the water---guess why you're having a problem getting it adjusted.

HTH