2 level 36,000 gallon Koi pond.

This 36,000 gallon koi pond with, 3 , air assisted, 4” bottom drains, 3Aquadyne 16000 Commercial Grade Bead Filters, 2 – 160 w UV clarifiers. The 2nd level pond designed to be isolated with its own filtration for either fish breeding or quarantining new fish arrivals.
36,000 gal koi pond top basin
View from the 7680 gal top,  breeding/quarantine pond basin, toward the main pond. 
6 years after pond completion the client asked us to add this fountain feature. It consists of a man-made Boulder with a 2 inch fountain jet molded in and, powered by and independent 5000 gallon per hour pump. The original rock this boulder was molded from weighed in at 2300 pounds. This man-made version weighs 215 pounds. 
36,000 gal koi pond build 1
36,000 gal koi pond build 2
Various suction, return and bypass lines heading toward the filter area.
The sand base tapers down from the wall toward 1 of 2 bottom main drains. the 2 lower inlet fittings are return jets, to push debris toward the main drain and promote circulation at this far end of the pond. the upper fitting is 1 of 4 waterfall bypass for cold weather filter operation.
36,000 gal koi pond build 4
There is a slight rise between the 2 bottom drains tapering toward each to help move debris across the bottom of the pond. Rubber liners shrink over time, it is necessary to leave extra slack for this shrinkage. Water pressure will push all of these folds flat against the walls. The wall shell is constructed of cinderblock to support the weight of the stones and prevent cave-ins. The liner will be cut  for the inlet fittings after the stones have been cemented in place, it’s final adjustment and  cleaned.
36,000 gal koi pond build 5
The top pond has a completely separate liner that overlaps the lower ponds liner. As long as there’s an air gap between the two bodies of water is not necessary to seem the joints. If there is no air gap you must seem the joint watertight. Again the wrinkles in the wall will be crushed tight with water pressure but, the floor must remain smooth to promote proper circulation of debris.
At this point the pond is being filled for the final time prior to introducing the fish. the koi were in a temporary 5000 gallon holding tank with full life-support while the pond was under construction. for the safety of the fish it was necessary to get them into the the larger body of water for their health and safety. The bottom drains were temporarily plugged while the filter system was under construction. To the left is the intake to operate the temporary filters. To the right we are filling the pond through the  water meter to determine exact exact gallonage for medication and chemical treatment.
pond skimmer
We prefer to use this type of skimmer because of its practical properties. #1 it is produced for the swimming pool industry so parts are readily available at a fair price by several distributors instead of just one. #2 It is pretty much immune to frost damage and if damage does occur repairs can be made easily without affecting the water containment system, or, rock work unlike box filters that are part of the side wall structure. #3  The weir draws water and debris from 360° and can operate with 5 inches of water differential. #4 it is scalable by linking several together according to the size pond they are working in. #5 baskets and other parts are easily purchased online at a FAIR price.
36,000 gal Koi pond view toward the entrance
36,000 gal Koi pond view as you drive in
36,000 gal Koi pond filter system 1
36,000 gal koi pond in the sun
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