My local home Depot & Rona keep their pond liners & stuff all year long. Yes, they are outside in the snow, but you can get at them.
You can make a 2x4 box & drape a pond liner in it to make your winter quarters. You will need something like 100-200 gal
for those fish. Failing that, try using big 50-100 gal
storage bins & your pond filter.
While the fish is in the 30 gal
, I would suggest:
1. Drop the temp and STOP feeding. Lower temp decreases the fish's metabolic rate & decrease NH3
production. Ditto for no feeding. If you can get the temp dowm to 4-5 C, you can get the fish to hibernate. Even putting the tank in a cold room in the cellar will help. I am not advocating this, but some guy hibernates his pond fish in little rubbermaid containers in his fridge. If you can get the fish to hiberante, you won't need a lot of water.
2. Do LOTs of water change - 50% or more daily until you get the NH3
down, and remove as much MULM from the gravel as possible. <Actually, golds can tolerate 100% changes pretty well, so you can't overdo the water changes! If it was me, I'd do a couple 80% changes today to get the levels down quickely.>
3. Use an ammonia binder like Prime as a stop gap.
4. Add some salt - you will run into nitrite posioning soon .... in addition to the NH3
. A little salt (like 0.05%) protects the fish from NO2
Big comets & kois are too nice to be put down without a fight .... so I would do that only as a last resort. Even if you have to do daily pwc
, it won't be too long before spring is here. And with global warming .... this might just be a matter of a few weeks! <Wishful thinking I know, but I am sick of our -20 weather.