Premium Member
Hi Frank,

In your recent article on skimmer, you mentioned the word "dry foam". can you please explain what this mean? Is it preferable to have dry foam as opposed to "wet" foam?

Also, I have seen sometank where the skimmate is gunky-mud brown and some which are murky green. Are there any hard and fast rule regarding the skimmate color (ie. brown = more waste?)


Thanks for the question.
This is were i will sort of step back, dance a little and say. Foam is foam. Its is unclear whether it is best to have "dry" foam, "wet" foam, tea colored foam, or clear foam".
In the article I used "dry foam" as an indication of how much processing was going on. It really isn't truely dry foam, but foam which has body to it. As you know dry foam means the foam sits in the reaction tower and as the air rushes past it, it dries out, it acts like a little chunk of foam. So truely dry foam is probably not a good thing.

I think the current philosophy is to have slightly dampish foam w/ a decent coloration to it (again not set in stone-since we can't see many of the organics). BUT this is and will be dependent on what you feed. your fish composition, and what your skimmer can remove.

We had been discussing foam eariler today and Steve Richardson threw out a nice tidbit which i would like to reiterate"

""Most skimmers can produce a dry foam.. but I dont believe that the goal. That just means that the foam has been in process for a long time and has dried to something like mud. Personally, I think a somewhat thinner skimmate can be more effective (exactly because the foam is in process for *less* time and provides less opportunity for some waste to get back into the system) and potentially removes even more polutants from the tank. This is frequently debated.

I also think that 'stinky skimmate' is misunderstood. Skimmate actually always smells pretty fresh and clean when it is first generated. After it sits around for a day or 3..yeah, it can choke a goat... but the foam produced doesnt smell any worse than your tank."""

How does your tank look? do you notice any yellowing or discoloring in your water?
Thanks for the clarification.

My tank looks normal, but I am fighting an uphill battle with hair algae at the moment. It is a 170g with DSB, LRs, Turbo Skimmer, carbon and refugium (set up for less than a month). All parameters are fine except for PO4 which is at 2.