Easy ? Wet/dry

[dvdj65]

can someone explain what is wet skimming and dry skimming I think I know but I would like to be sure.

[Fat Tony]

wet- light tea colored skim, more watery.. dry- dark nasty skim, drier, not as much water in skimmate

[chrischris]

there ya go
you can acheive this by raising the base level of foam higher for wet and lower for dry

[motorslave]

To get wt skimming, raise the water level in the skimmer so the foam is close to the top of the neck, to get dry, lower it.

[dvdj65]

is there pro or con to either method?

[chrischris]

with wet skimming you get more crud out of your system
but you have to empty your collection cup more offten
with dry skimming you get less crud out of your system
but you can prolong emptying your skimmer for a while(i skim dry when i go on vacation but wet when im home)

[motorslave]

There is actually more to it than that. What it is I don't remember. maybe Tom will pop in an give us a dissertation on it!

[dvdj65]

ok thanks

[chrischris]

ya i just gave you the extremly simplified version

[aquawolf]

I'm tagging along in hopes that Tom will respond as well.

Good question David.

[dvdj65]

Tom oohhh tom where are you? LOL

[snow_man84088]

Originally Posted by aquawolf

I'm tagging along in hopes that Tom will respond as well.

Good question David.

Ditto!

[dvdj65]

Hmmmm, bump =)

[tdwyatt]

Tony brought this to my attention.


Although there are more than just the advantages of removing the particulates and more DOC's from the water column by wet skimming, it makes controlling your salinity much more difficult. If you wet skim, you need to replace a volume of seawater equal to what you skim off every day, then measure your SG to determine what you've lost in terms of evaporation so you know about how much FW RO/DI to add to make your salinity 35 PPT. This means that your salinity is going to be varying each day based on reestablishing your proper salinity once a day, much like having a once a day top off system with normal or skimmerless systems, as there is not a simple way to determine what your evaporative losses in a day with such a rapid loss of saline water via the wet skimmate. If the system is having problems, and there are issues with heavy phosphate and/or nitrate as may be demonstrated by heavy or rapid algal growth on the glass, then blasting the rock with a power head and heavy siphoning to remove detritus from rock crevasses and running your skimmte very wet (to remove the stuff the "blasting" suspends) would be in your best interest, but only for short periods of time. If there were some way of determining with a "salinity controller" the salinity of the water column, you could connect it to a source of ASW and RO/DI so that it would correct your salinity by adding either ASW or FW to the tank to make it right, however, I am not aware of such a device to maintain constant salinity for creatures in the tank. Such fluctuations make it very hard on captive corals and the inverts we like to keep (like snails, shrimps, and echinoderms in general, etc.). Ideally, you would adjust your skimmer to wet skim while blasting the rock and corners of the tank to suspend detritus, run it that way for 4 or so hours with any ATO devices turned off, then correct your sump level with ASW and correct your salinity to make up for whatever evaporative water losses occurred in that short period, then turn your skimmer back to dry skimming an turn the ATO back on once salinity and the sump level have been corrected to the norms.

In actuality, it there were some way to automatically correct for the salt loses represented by wet skimming, as well as correct for evaporative losses without a constant "zero" starting point for system volume (how the ATO's work now), then I would rather have wet skimming all the time. Wet skimming removes more of the DOC's before they have a chance to decompose (remember that they decompose to source out constituent levels of phosphate and nitrate), it remove more particulates, and it performs an automatic method of water change depending on how much water is lost with the level of skimming the aquarist selects. However, there is no way currently available at a reasonable price to do this and still keep the salinity stable. This leaves wet skimming as either a once-a-week method to use for tank cleaning days or relegated to the use by those that have lots of time to maintain the system salinity manually each day or multiple times a day (or for those that 100% flush the system once a day with natural SW with semi-open systems, but these systems really do not even need skimmers, so this is kind of moot).


HTH

[tufacody]

hmmm, i thought that wet skimming was also more likely to remove important trace elements, and that this was the con against it. I can certainly see the salinity argument for smaller tanks though