Hello everybody!\nFirst let me say, Im so excited to have such a diverse group of "friends" with the same fish fettish (as my husband calls it;) ) as I do. I look foward to picking everyones brains!\nOk i was bitten by the pond bug about 8 yeard ago when I purchased a house that had a medium sized pond already in te back yard. The pond construction itself was rather poor ( just a large hole with a liner, a submersible pump attached to a small internal filter, and a hose that ran out of the pond behind and over a pile of broken up concrete chunks! The pond was extremely easy to care for ( Im assuming because it had been there for many years and was well established). I deeply enjoyed that pond for 5 years. After purchasing a newer house with a "blank slate" back yard, a pond was a must for me! So after much persuasion I finally convinced my husband to give me a corner of the yard and we began digging.......\nAnd 3 years later, we just finished!! We agreed that with this pond we were going to take our time and do it RIGHT! We dug the hole, which was approx 12'L x 9'W (in the widest part) and 4'D. We did a sloping base with a large bottom drain in the center. We reinforced the diagonal walls with metal lath( due to our sandy soil), placed an underlayment material, followed by carpet padding, layed a 40mil(I believe) liner, lined with chicken wire and then coated with type S mortar. We installed a Laguna Skimmer filter and a Laguna Filter Falls (rated for 5000gallons each) and a large 3 tier waterfall. \nUnfortunatly, we had not filled the pond yet when we experienced a pretty hard freeze here in California. So after 3 years of construction and much anticipation we filled our pond and woke up to it half empty the next morning. By that night it was 3/4 empty and i cant even explain the heartache:sad:\nWe were told that mortar does soak up alot of water, so we filled it half way up again, knowing in our hearts we had a leak, and it drained again. Well after SEVERAL attempts to fix the promlem the only other option was to fill the bottom drain ( which had cracked in the freeze) with concrete.\nWe let the pond hold water for 2 weeks, drained, filled again, and cycled for another few weeks. We added 8 - 6" koi. The koi have been in for almost a month now, but pretty much stay on the bottom all the time. Im hoping its because the water temperature, wich is saying in the high 40s - low 50s.\nI do have a few questions:\n-Does the bacteria die off in the winter?\n-I have a large (265g) aquarium with 2 fx5 canister filters for my oscars in my house, should I put some of the filter media into my skimmer/ filter falls to seed it?\n- Is there anything I should be worried about with my fish staying on the bottom?\n- also, I have been turning the waterfall off at night ( when the temp drops) for approx 8hrs in order to prevent the water temp from dropping even more. Is this ok? I figured with such a small fish load they should be ok. and in the spring and summer i do plan on running it continuously.\n\nSorry for such a long drawn out story! Again thanks in advance, and I am looking foward to chatting with everyone.