I appreciate the help, but the lecture on pond size, koi, and bigger is better was really unnecessary. My pond is the size it is for a reason. I asked a question for skimmer recommendations. I understand that housing koi in a small pond is a big issue, but it's kind of a turn off when all new members are greeted with the assumption that they haven't done any research. My original post said nothing about koi.[/QUOTE]
Sorry if I seem to come across like that, I have posted in another thread. I post like this for a reason. I may be answering your question but I post so that someone that hasn't done research or doesn't really know what is going on may benefit also. I've worked in the pet business for years, and worked offshore where guys come in with years of experience and yet don't know anything about what we specifically did on our jobs. So please take what information you need from the post and remember that I post for other members as well not just to the one person asking as I have not seen your pond personally and don't know all the details. Just trying to help. Also keep in mind I do keep koi and there are things that need to be considered if someone may be wanting to raise them.
IMO, I would add a skimmer, as far as removing foam, all it does is remove it from the surface but what caused it will probably still be in the water and needs to be removed to actually clear the foam issue up, But skimming does help greatly in increasing Oxygen levels, removes leaves from the pond that would cause bigger problems later and it makes maintance so much easier for you in the long run. Plus it puts a lesser load on the Bio filter and allows it to do its job a lot better.
Again, I'm sorry if I sounded like you didn't do any research, not my intentions at all. I'm simply trying to help answer questions and give reason behind my answers for all to be able to use.
BTW, I figured up your pond in gallons by your desciption and your wife is really pretty close, without the shelves it would be about 960 gallons, taking the shelves and all into consideration I think the 600 gallons is on the low side of the estimate, 750 gallons would be on the high side. Again she may be right on the money, just wanted to check and see.