Going homemade... (very long)
Hi,
Try adding more oxygen (additional pump) and some shade too if possible.
A year and a half ago a who neighbor who was moving gave me a 120 gal preformed pond and a big pump, he had just used it as a water feature. It is above ground next to a deck. So you still look down into it.
I hooked it up as a water feature, but wanted fish, and I treated and cycled the water to be ready. It was going into winter time so I wasn't in a hurry to put fish in.
Real pond filters cost a lot of money and I wasn't totally sure I wanted to invest that kind of money if I changed my mind, or whatever, not the kind of thing I have money to spend on anyway.
So this is what I did...
After doing a bunch or research on what the filter is basically for filtering out debris and sediment, and what it does, produces good bacteria, I made my own "trash can" filter. It is (was) a new plastic garbage can ($3.00 from the Habitat for Humanity ReStore).
I took 1/2" irrigation tubing left over from my drip irrigation project and used the pump on a cement block with tubing to pump water into the can and enough to go over the top and down to the bottom and around in circles several times in the bottom 4-5x maybe. (pump on the block is for safety in case all your water gets pumped out into the yard, there is still water below for the fish to survive)
Then went to Home Depot (HD)and asked for what I wanted, and they didn't have such a thing (which was a landscape drain box, smallish, maybe 6"x10", I have seen in Texas HD, not my local Colorado store, so I wandered around the plumbing dept. until I found what I thought would work. I found a PVC 45 degree elbow, I can't recall if it had real name, but it was white and had a thick fat half of the elbow, like a female side and on the other corner a thinner, male side. I took the diameter and positioned it up to the height I wanted, mine is appx. 10"down 2" to make a 2" diameter hole with a Exacto pen.
Slid in the skinny side of the elbow through so the fat side of the elbow faced up and open parallel to the top of the can so water will rise and fill the can to that level and pour into the hole like a drain. I put a fat snake like ring of plumber's putty around the elbow and can, smoothed it around to make a thick good seal and let it dry, on the outside I added a thin one and I took a hose clamp and added a piece of vinyl hose 2 1/2" in diameter which comes in a roll at HD in the tubing section, it is blue and lays flat like a fire truck hose and looks like the liner in a above ground swimming pool.
***Huge important tip for the flat vinyl hose, put the crease toward the sky and the ground so when flow is reduced it doesn't collapse on itself and back up your water flow out of the trash can and into the yard - Personal experience. LOL I actually inserted a length of PVC pipe into it to assure it stays open because my plumbers goop had attached to the tubing and I didn't want to do it all over again.
***Also I would probably add an overflow tube above the gravity drain, "just in case" there is a blockage and you get a back up.
My filter is next to my pond so the water flows in like a water fall. If you are putting it farther away, or under a deck, etc. just use what ever pipe you want, flexible, or rigid, so you can get the water from point A to point B.
For media you can go as expensive as you want. I had very young, small fish, so I went discount, what I had available. I used strips of blue evaporative cooler material I cut probably 6-8 feet long worth, some I cut into 4" chunks to fill in around the strips and a couple of large bundles of filter media, packed in pretty well all around the coils of tubing in the bottom, used a cement block in the middle with two can size squares one angled like a diamond over the other to keep the strips in place with a brick on top to hold down better. Took a plastic basket from an evaporative cooler and put it up against the area where the gravity drain is to keep extra gunk from filling it up and took a chunk of filter media and put it behind to catch any other debris, and finally just because my neighbor brought it over added a 10" nerf ball on top. I have a piece of wood as a top so the cat can sleep on top and watch the fish LOL.
This year I am planning to add bunch of Bioball type things to boost the power as my fish are getting bigger and It is funny how everyone wants to give you their big goldfish when they outgrow the tank when you say you have a fish pond. Ha ha
I added my old fish tank water to it to help even more at the beginning, then after all was wonderful I added my fish which had been growing inside during the fall and winter. Always have had perfect water.
Added an out door umbrella to give partial shade during the summer, and lots of water hyacinths. Here they die in the winter. Scrub off algae from the sides on occasion. Also added a second pump for aeration and the fountain thing. And a real 8" Japanese glass ball fishing net float. This year I am thinking of adding a Pergola with movable shade cloth, wind broke my market umbrella.
Also considering adding 1-2" river rock on the bottom.
My neighbor brought me a net he had in the garage and I bought outdoor/camping quality elastic and wove it around the outside and snapped it around the edge. Used uv resistant little zip ties to gather excess net at curves and twist ties if it is in a spot that shouldn't fall into water This keeps out leaves and so far discourages predators. We have many predator birds.
Because of many items I had on hand, for this experiment, I think I spent appx. $12-15. Sorry for the length of the post. It was a fun project and my fish are happy, 4 butterfly koi and 3 beautiful "used to be feeder" goldfish.