John,
Should be a problem unless you have fish like bi color blennies that like to back into things and sit when they aren't on...
For all asking how this is going to work, we talked today and decided that each member will be given the first mod for free, but will have to pay the cost of the other mods. No pumps will be provided, though. Trying to be responsible with spending, if we allowed more than one mod (~$7 for parts), we would quickly eat all of this years funds per member. I will want three of them, so that would exceed my membership dues for the year.
What we need to do is determine who wants how many of what. I can keep a spreadsheet of the info and post it several times before the deadline (TBD) so that we know we have enough time to get all the parts in. We plan to modify the parts the weekend before (as Chris mentioned), so any willing/able to help out that weekend will be appreciated. Rick's neighbor has offered his workshop up, so we can build each section in groups and knock it out quickly. We will then do the gluing, etc., at the meeting. The mods twist onto the pump like the normal impellor housing, so you don't really need a pump on hand to do the mods. I'll star another thread strictly for keeping a count of the who's, what's, and how many's. For my sanity, if we can, I'd like to keep this thread the questions thread and have the other one be the count thread. Chris has found the place to order parts from, so he will do the ordering for this batch. He is also the one that can answer questions like what exactly is the difference between singles, doubles, and large props, etc. We are looking into an form of attachment better than what we have now. The cost of those parts has not been determined yet, but will be offered as an option (if the cost if feasible-gotta check that out tonight, hopefully). Hope that helps answer some of the questions

.