Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Don't cycle with fish.
Ammonia burns their gills and fins. Think of the worst sore throat you ever had. So bad it hurts to breathe.
Nitrite causes 'brown blood disease' Google it. Makes the blood not carry oxygen very well. So, on top of the burned gills, the fish now need to breathe more efficiently to get more oxygen. Some fish die. Some survive but remain delicate the rest of their shortened lives.
In addition, feeder Goldfish are not treated very well and can introduce diseases and parasites to the tank.
At this point I would:
1) Return the Golds.
2) Sterilize the tank.
4) Begin a different method of cycling.
There are a couple of ways you can go.
Add a bacterial additive. Make sure it has Nitrospiros bacteria. All the other additives are the wrong bacteria. The right products will proudly advertise "Nitrospiros sp.". The wrong ones will say 'Faculative bacteria', 'helper enzymes' and similar things. The right products can cycle the tank pretty fast (few days, less than a week) and with just a small blip of ammonia and nitrite. A good way to use them is to add a full dose, then stock about half the fish. Keep the rest in the fridge, and add more of these bacteria when you add more fish.
Fishless cycle as mentioned above.
Add ammonia to 5 ppm. Test daily. When ammonia starts dropping test for nitrite.
When nitrite shows up keep adding ammonia, but just to 3 ppm. If the nitrite goes over 5 ppm, do a water change. These bacteria do not grow well if the nitrite is over 5 ppm.
Keep on adding ammonia to read 3 ppm.
After about 3 weeks from the start the ammonia and nitrite will be removed in less than 24 hours. The tests will show 0 ppm for each of these, and the nitrate will be really high.
Do a big enough water change to drop the nitrate to safe levels, and add fish. This method grows so much bacteria you can fully stock the tank all at once.
Doing this in a planted tank is a little different. The plants may not like 5 ppm ammonia, so I would just go with 3 ppm throughout.
The cycle may go faster because the plants can introduce some of the bacteria you are growing so the cycle is jump started. Also, the plants themselves are removing some of the ammonia and nitrite. They are part of the bio filter. Still, keep adding ammonia and monitoring it. When the ammonia and nitrite show 0 ppm within 24 hours of adding more ammonia, the cycle is complete. You can add a full load of fish.
Really fully plant the tank, and make sure there is enough light, carbon and fertilizers for the plants to be really thriving. Plant so densely you cannot see the back of the tank.
Add 3 ppm ammonia and see if they can remove it all, and no nitrite shows within 24 hours. If the plants can do this, then it is safe to add fish. I would stock at 50% and keep on testing, then stock the rest when tests show that conditions have stabilized.