I am a long time lurker and have gotten many great tips from the folks here so I thought I would post some pictures/instructions for building a trickle tower that I made last summer. I was not sure until recently how well these things were working, but I had to take this one out of service to repair a leak and we noticed the water clarity started suffering after about 3 days of having it off line. The water leaving my sand and gravel filter comes into the top of the tower and falls through layers of shredded plastic water bottles to the bottom of the drum where I put 2 bags of lava rocks, and goes out a shower drain to a minature foam fractionator and then back into the pond. When I took the shredded plastic out of the tower I noticed that you could see by discoloration the path the water was taking and it was only going through a small portion of the plastic. I solved this by taking a plastic planter base from home depot and drilling a bunch of 9/64 inch holes in it. Now the stream hits the planter base and spreads out, dripping over most of the plastic media and hopefully working better. Ok on to the build:
Step 1 Take a plastic drum and install a shower drain that takes 2" PVC pipe. I used PL Pro Line to seal around the shower drain.
Step 2 Attach the drum to the foam fractionator or return line to pond. I live in a little town and our hardware store only had 4" pvc pipe, so that is what I made the fractionator out of. I am not sure how much the fractionator affects the water clarity, but it makes a rope of dirty foam most nights so I am sure it is doing some good. On either side of the fractionator I stacked 2 cinder blocks for the drum to sit on.
Step 3 Drill a bunch of 9/64" holes in 3 plastic planter bases, we got ours from home depot and you can put them together and drill all the holes at once. Note to men: criticizing how fast your wife does her share will result in you being left to do all the holes yourself.
Step 4 Spread 2 bags of lava rocks in the bottom of the drum and place one of your drilled planter bases in the middle of the lava rocks.
Step 5 Take half of whatever media you are going to use to grow your bacteria on and put it on top of the planter base/lava rocks. Like I said earlier, I used shredded plastic water bottles it was a little time consuming running them through the shredder but they were abundant at work and free. On top of this layer put another planter base, then a second layer of media, and finally the last planter base.
Just adjust the pipe coming into the tower so the water stream hits in the middle of the planter base and you are done.