I have three large “Skippy” filters on three different ponds and a couple of smaller ones on the goldfish ponds. They are simple to construct and do a very good job of helping to clean the water. Basically, water is pumped into the tank through a system that feeds through the bottom allowing the water to rise up through the filter material and flows out through a 4 inch pipe back into the pond either directly or through a waterfall.. I use 1 1/2 inch pipe to pump the water in and in my case, a 1200 gph pump located in the skimmer box.
Basically, mine are built using a 100 gallon Rubbermaid tank that I buy from the Tractor Supply store, one of my most favorite places to visit. I have mentioned before that in real life, I missed out and should have been something related to the land like a Farmer or Wildlife Warden hence my liking for Tractor Supply. I guess I am compensating in a different way. Anyway, Tractor Supply carries these Rubbermaid tanks in different sizes and I have found that the 100 gallon size is just right for my purposes. I also have three of the 80 gallon size that I use to keep pond plants in as I am getting them ready to put into the ponds or to over winter them.
The tank on the 5000 gallon pond developed a leak very close to the drain plug that is built into the tank. It was only the very faintest of cracks but enough that it was constantly dripping. Over time, this would amount to a lot of wasted water (and money) so I decided that I would do a repair job on it.
I shut it down and drained the water back into the pond and disconnected the plumbing. I then emptied the filter material which in this case was Lava Rock loosely stacked inside of the tank.I was surprised how clean the rock was as I expected it to be pretty muddy considering that the system had been in place for at least 10 years. Turns out that most of the mud was in the bottom water chamber built into the system. I finished cleaning out the muck and put it on the garden as it is basically fish poop and full of good garden nutrients. After washing out the tank, I turned my attention to finding the leak from the inside as I already knew where it was generally located from the dripping water on the outside.
I found what I thought was the crack. It was about 3 inches long and in a difficult place to repair. Being a Rubbermaid tank and with the basic material rubber, I opted for a tire repair kit to see if it would seal the leak. I have a small electric hand sander which I used to prepare the area, cleaning and roughing up the rubber tank material and after cutting a patch from a small piece of pond liner (another rubber material), I carefully applied the adhesive and after waiting the appropriate time for the glue to dry, applied the patch over the crack.
The repair was as good as I could get it and I went about the task of putting the filter back together. I like to build a chamber where the inlet pipes are located to give the water a chance to flow freely before it rises up into the filter material. The old material that I had used for this chamber (a wire shelf cut to size) was not in very good shape after many years under water so I decided that I would replace it with better and stronger stuff. This meant a trip to Cedar park, around 30 miles one way, to visit one of the Pond Society sponsors, Hill Country Water Gardens, to purchase the proper material. I needed a 2 by 4 piece of plastic grating and a 4 by 4 piece of plastic mesh to put on top of the grating to stop smaller pieces of the lava rock from filling the chamber below. Even though it is a long way to go, I really like visiting this place as it has so much cool stuff. I should mention that prior to making the trip, I put enough water into the tank to cover the repair to test the leak and it seemed to be holding up.
The next day, I carefully cut the grate to size followed by a piece of mesh also cut to size and after replacing the fill pipe from the original setup, installed the grate and mesh into the tank on strategically placed bricks for support after making sure that the tank was level and well supported although I had not moved if from its original place. I opted to buy some mesh Laundry bags from a couple of the local stores and to load them with the lava material as it it had been a real bitch to dig out this time around. As I filled the bags, I placed them onto the grating inside the tank until I had enough for my purpose. I used loose lava rock to fill in any holes between the bags. After reconnecting the original plumbing, I turned the pump back on to see if everything was working as it should and that it was not leaking . It appeared to be OK so I left it running overnight.
The next day, to my dismay, I discovered that there was a second leak that had not been visible the first time around. I figured that probably loading the tank with the lava rock and with its additional weight, had distorted the tank enough for the second leak to show up. I left it for a couple of days but it was only getting worse and was really bothering me to waste that water, even small drops at a time. I decided that I would do the job over this time with a new tank but that is a different story. You could say, part two…