Hey smilinbear. The goo is from chlorine reacting with your biguanide. I'm not sure why no one has told you about this yet . The solution is a bit problematic. When you replace your water it is full of city chlorine. You need to either leave the tub open for a couple of days to release the chlorine as gas through the air or dechlorinate with a chemical. If youy dont do this the sanitizer will react with the chlorine giving you GOO! Just topping off your system with chlorinated water will create some goo. I actually use a five gallon bucket and dechlorinate it before i top off. This seems to have stopped my goo problem.
Beyond all that I seem to have repaired my water mold problem. Here is the process.
take out and replace filters. if the filter is very new and expensive you could try chemically cleaning it for at least 24 hours.
Drain all the water from the tub, every bit. Use a wet dry vac and try to suck out water even from the jets and intakes. You'll never get it all, but get a bunch.
fill your tub with water. Leave the filters out(they shoul already be soaking if you are not buying new.)If you can, buy some of the enzymes available at the links at this spa site. and use as directed. (Mind you that I did not have any enzymes and had to skip this step. next time I will probably use them.
add 1oo ppm of dichlor. For a 500 gallon spa that is about 13 oz.
run the spa continuously for 24 hours without the filters.
turn on and off the blowers occasionally for several minutes at a time but keep the filter motors running.
you dont need the heater on because you are going to dump this water.
Drain the tub. If possible blast some water through the pipes after draining this might knock some stuff that just layed in the pipes after draining.
Vaccuum the water out completely. There should be alot of white crap in the bottom of the tub. This is the mold. So you want to throughly clean the sides, filter box ,anything that has gunk on it. Rinse the entire tub with fresh water. Drain and vaccum completely again.
Fill the hot tub and run it with the air jets on and the filter back in. If using biguanide leave the top off or dechlorinate.
After one or 2 days rinse your filter out with a high pressure hose because some of the gunk will still be moving through your system.
You are done.
I have had crystle clear water for 2 weeks now. I'll let you know about how long it lasts.
I will be switching from baqua to leisure time biguanide. The base chemical is the same(hydrogen pyroxide) but they are not as dogmatic about their use with other products. Remember the best way to be sure you have a water mold is when your pyroxide dissapears in a day. That is because the mold eats it up. So if your oxidizer level dissapears right after you put it in you have water mold.
Good luck