The talk on filters has prompted me to ask my own hardware question.
I have a 100 gallon walstad tank, and I recently put a little air stone in front of one of the pumps to make sure that everybody is getting whatever dissolved gases they want. The problem is that the air pump is really noisy. I replaced it with a newer one (but still the smallest and cheapest), but that was just as loud. I'd be willing to pay a premium for quiet, so any recommendations on some more silent brands?
Also, any good way to get all the tannins out? Between the dirt and two pieces of driftwood, my water is very yellow. I keep hoping the duckweed and water hyacinth will suck them up, but that doesn't seem to be the case, and I'd rather not resort to filters and activated carbon.