Koi Rescue
Phoenix Arizona

Install Window Fiberglass Koi Hatchery Tank & Quarantine Tank

I have become addicted to looking at my koi through a window, so I started by installing a window in the tank.

Pretty simple, just a hole in the side of a tank, a piece of lexan (which is like plexiglass, only stronger and UV resistant), and some 3M5200 adhesive to hold the window on the tank.

The 3M5200 glue is commonly used for sealing hardware on boats. It is rather a pain to work with, it takes 48 hours to get tacky, and another week to cure down to 1/8". To make matters worse, I was doing this in January so the day temperatures were right on the edge of the suggested curing temp, and night time was way below it.

To hold the window in place during the curing process, I used a couple of sticks from the bottom of the window to the bottom of the tank, and then used a shower rod to press the window against the tank. To keep the temperature in the curing range, I suspended a light bulb inside the tank.

Few pieces of cardboard to cover the top and retain the heat. It worked really well - I left it with the cover for 5 days, then let it cure for another week without the cover on.

The trick to keeping big koi in a small space for extended periods is to:
1 - highly aerate the water (packed column aerator)
2 - have a high turn over rate of the water (large pump)
3 - create a current for them to swim in (circular tank)
4 - continually change the water

Items 1 through 3 are easy, so I needed to figure how I was going to handle the water changes. Some koi keepers have a trickle system where they continually drip in a small amount of water, with an overflow to direct the extra water out. The 3 issues I see with that are:
1 - the tap water has chlorine in it, and if the flow rate is too great, or the city puts in a high level of chlorine, then it will poison the fish.
2 - the water that is leaving the pond is a mixture of the new clean water, and the old pond water, so it will take a larger amount of water to make the same net change.
3 - if you are draining the overflow water to a spot on the ground, it will be continually muddy there.

So I decided that I would rather do regular drain and fill water changes. I plumbed the tank so all I needed to do was open a valve and 30% of the water would rain out. Then I'd add dechlorinator, and use a water timer to fill it back up again. I have an overflow too so it will keep the water from spilling over.

I have a lot of stuff that lingers around my koi tank, like koi pellets, water test kits, nets, spare pumps, dechlorinator etc. Figured if I was going to have this on potentially the front porch of an apartment, I wanted a handy close place to put this stuff, but be able to lock it so people wandering by wouldn't liberate my stuff.

The barrels in the back are what I was going to use for transport while carrying them in my boat as I drove across the country.

So I made a stand for the tank to sit on which has a couple of drawers to it.

I made a box for the top of the tank to organize my power cables and store extra stuff like the UV sterilizer, light on a timer, digital thermometer, and just extra clutter.

Final problem to solve is that the window is made of Lexan, and my dogs occasionally paw at the window. To keep them from scratching it, I made a flip down window on the outside.