KOI Pond saved!

July 16, 2008 @ 3:19 pm · Filed under Ponds-Koi

Thought I’d share with the group my near loss of pond, recovery, and lesson learned. Specs. 1,700 Gal. pond, Performance Pro 1/4-49 pump, Ultima II 2,000 filter and Aqua UV 80W. Aloha Oregon, near Portland. 6 total KOI about 100″.
Trouble began when the water was more green than it should have been. The pond was not originally designed for KOI and is 1′ deep at one end and about 28″ at the other and gets no shade. I thought it was some simple thing - a few hot sunny days. I turned the filter valve from 1/2 to full. (The pump output is split between a waterfall and the filter). Didn’t get better, so the LFS guy said let’s measure the chemistry of the pond and see what’s happening. (DUH! When I measured it, PH was 5.0. You read that correctly. I was embarrased. Immediately dosed with baking soda and got the PH back up. A couple of 25% water changes too. The water was still too green, so we added another 57W UV filter and that seemed to help, but not clear it up. The KH and GH were both about 1.5. Turns out that’s about what my tap water is. So a regimine of adding CaCl2 and baking soda began until the pond was up to about 5.0 for GH and KG. PH now 8, but nitrite was up. Salted to .1% to help the fish. Every day I monitored NH3. It kept creeping up to .25 by morning, so I’d add cloram-X. Next day OK, one more day, back to .25! The nitrite had dropped to zero for several days, so we couldn’t figure it out. I kept backwashing my filter, but it looked clean. Then I decided I need to measure the actual flow from the filter. Low and behold - 300Gal/hr., much lower than it should be. After some procrastinating, I opened it up - the jets were clogged with sand from a plant we had a year earlier that the KOI had knocked over. So I cleaned that out, got the flow back up to 1,200 Gal/hr. and now the ammonia problem is solved too.
Lessons learned: When you see trouble, measure everything you can.
Measure your tap water, get it to a respectable chemistry. Now when I do PWCs, I add baking soda, cloram-X and ClCa2. Make sure there’s buffering capacity in your water.
The pressure gauge on the Ultima II is useless! There was no indication that I had a problem with flow. This needs to be measured periodically too. Wish there was a better way than disconnecting, putting hose in a bucket and timing how long it takes to fill.
The fish are all fine and I’m a happy camper again
George