Fish Tank Construction

  • 12K gal koi pond with a stream back in Rochester, NY that we built totally DIY, 6ft deep, EDPM rubber liner (photos on the Yard is Canvas page):


  • Overview: biofilters, water turnover, water change, 12,000 gal/day Reverse Osmosis filter system, pumps, drains, etc.:
  • All our tanks (50K gal) receive a continuous water change 5K-10K gal/day; temporary cascading overflows (all smaller tanks overflow into the 25K); DIY bulkheads for liners:

18K gal 20x20x7ft sump & water reserve

500 gal mechanical prefilter

Three Don’ts from personal experience

Two 4 inch pipes for the bottom drains of the two 4500 gal tanks
  • Do not use RPE reinforced polyethylene liner for indoor applications, especially if it would have creases. It seems the creases result in small, slow leaks in my experience because I used this liner to line the sumps for ten 240 gal tanks, double layer, only to get a slow seepage (replaced with EDPM rubber). It’s probably adequate for outdoor inground applications:
Slow leak, water is seeping from the end absorbed into the white towel on the floor
  • Do not use garbage totes for a long term filter. Sump filter out of 100 gal garbage tote: 4.5ft / 135cm high, filled with 1500 nylon mesh pot scrubbers with three woven matts on the top. First set up as a part-time siphon / dump flow filter, cycling between filling / no flow and emptying / siphon periods. But later found to work better if the siphon was eliminated. Overall, works great but the construction of the tote is not suitable to hold 4.5 feet of water pressure long term. After 2-3 years it started leaking (not the connections but the body of the tote):