Let’s do a little math.
has 4 18’-20’ Koi and 4 6’ Koi.
Daily approximate Ammonia production is-
-assuming 2 18” and 2 20” fish =
18” = 320.5 mg x 2 = 641.0 mg/day
20” = 439.8 mg x 2 = 879.6 mg/day
6” = 11.85 mg x 4 = 47.4 mg/day
For a total of 1568.0 mg/Ammonia per day.
In a 1900 gallon pond this equates to 0.825 mg/g or 0.218 mg/l
This equates to an Ammonia level of 1.5 mg/l after only one week and will continue to climb albeit at a slower rate. A level of 1.5 mg/l can be an issue even at a water temperature of 50F.
Considering that the population of nitrifying bacteria takes almost a full day to double in size, using ‘seed’ water, though helpful does not grant Carte Blanche to return the full fish load to this pond. The bacteria population cannot be expected to keep up with the Ammonia production for the initial few days. Nitrifying bacteria when in the planktonic state are unable to oxidize either Ammonia or Nitrite. It is only when they are in the consortium of a biofilm can this process take place. Biofilm needs be reformed in this entire pond given a new liner has been installed. So there is no immediate Ammonia conversion taking place at any significant level.
’s suggestion of a ‘fishless’ cycle is the only logical, and safe, path to proceed assuming that the fish can be kept without issue in the separate holding tank. If not, the fish can be added one at a time over an extended period beginning with the smaller fish. Frequent monitoring of Ammonia levels must be observed.