Whirlpool Problem

Moved into a new place last spring. Master bath has a whirlpool (actually, a soaker tub that's been converted) which is nice, except for one problem.

If I don't use the tub for several days, water in the plumbing tends to get stangant and then releases brown/grey crud when the pump is used.

Other than filling the thing every day and draining it, or buying a 55-gallon drum of chlorine bleach, is there anything I can do to prevent this?

You've discovered one of the problems with this kind of tub. The manufacturers typically recommend a thorough cleaning with special chemicals in the order of once a month or so. My guess is that yours has maybe never been cleaned with the proper stuff. Check the website, or just a google search, and then pick up some of the chemicals recommended and try that. Usually, you use one, run the pump. Let it sit, then drain, then redo it with a different chemical. Since it hasn't been maintained properly, you might have to do it more than once to clean it up. Then, if you do that on a regular schedule, you can keep the thing sanitary.

I opted for an air tub...instead of pumping water around where hair, soap scum, body oils, etc. can get trapped (organic crud) and feed mold, etc., the air tub has a chance of staying fairly clean because you can run the air turbine when done and it air dries like a blow drier the internal passages.

Whirl Out from Home Depot might help your problem.

pump

Your main problem is probably that the pump is installed too low and therefore does not drain out when the tub is emptied. That retained water is what stagnates. The bad news is that if that is the problem it may not be correctable.