If you don't figure it out, I'm a bit impatient. I got my 55 gal plumbed and running a week ago this last tuesday. I seeded the wet/dry with a used cart from the HOB filtering my 20g. I dosed ammonia once and have been checking it every day...ammonia level didn't move, no nitrites. I guess I forgot to the check the nitrite results last night because when I got home from work today I notices yesterday's nitrite test is reading 2ppm. Today nitrites are reading 5ppm which is high as the test goes.

How much did you use in the dose? I'm going to pick up a small 20 gallon this weekend and want to do a fishless cycle, but although I've read a million articles on how to do it, not one of them mentioned how much ammonia to use.

You dose to achieve the ppm desired. Ammonia is sold in different concentrations. So my tsp per 5 gals may have a different affect from your tsp per five gal. If I had 1% ammonia and you had 3% ammonia, the affects would be different.

Yep^^^ dose then test...repeat but congrats on the cycle! mine took longer...and I was VERY impatient...

ChiaJesus, try a quick calculation. PPM is parts per million, think of it as ml per 100 litres if you want. Take a 20 gallon tank. It will hold maybe 18 gallons of water on a good day. At 128 ounces per gallon, a one ounce dose would be far too much but wait a minute, its not pure ammonia. At most its 10 % so you get 1 part in 1280 with an ounce. That's still way too much but figure an ounce is 2 tablespoons or 6 teaspoons. If you use a teaspoon you have a part in (1280 x 6). My calculator says that's one part in 7680. What is that in ppm? Invert and you get .000130 or about 130 ppm. A teaspoon is about 5 ml so how much for 1 ml? 130/5 or about 26 ppm. Hold on, I haven't used the 18 gallons yet. 26/18 is only about 1.44 ppm. I want 5 ppm so if I'm using 10% ammonia it looks like 3 ml should get me close. Next step is to put in 2 ml and measure the result. Maybe I forgot something so I'd rather go light. If I see about 3 ppm then I know I'm on the right track and just add another 1 ml. If I get some other number that is lower, maybe I don't have 10% but have 3 or 5% ammonia instead so I adjust. If its a little higher but under 5 ppm, I'm still OK and maybe I don't quite have 18 gallons in the tank. The basic appoach can be applied to any tank size. Now try it in metric units. You have a 70 litre tank and are using 10%. Your target is 5 ppm. Starting point is 1 ml gives 1/10 part in 70000 ml or 1 part in 700000. Divide and its 1.43 ppm. Same basic answer but a lot less conversions involved.

Gotcha. Thanks for the info, I'm learning so much! My new "small 20 gallon" tank actually turned into a pretty fancy 48 gallon tall tank for the living room. I would rather not put innocent friends through a fishy cycle. I'm going to print out this page and do it right this time.