Question about the fishless cycle method.

[Orca]

I’m going to attempt a fishless cycle (raw shrimp method) for a new 75 gal FW community tank that I’m setting up, and I have a question about exactly when to add the fish.

I assume that the timing is critical because you don’t want to add the fish before the cycle is complete, yet if you wait too long, you’ll lose the ammonia and nitrite eaters from starvation.

So when should you start to add fish, and what number of fish is recommended initially to the provide the bio-load to keep the cycle going? (OK, so that was two questions.)

Thanks!

 

[astroguy]

with a fishless cycle (with pure ammonia), you add the fish... at the end, when the tank is cycled!

 

[tkos]

When you have consistant readings of zero across the board you have about 24 hours before the bacteria start to die off. It won't die off all at once but capacity will decrease. And if you only add a few fish at a time there will be some die off to match the new level of bacteria. Just keep those test kits handy.

 

[Orca]

“..you add the fish... at the end,..”

Ahhh, but what is “..the end”? Is it when I have Nitrates and zero Nitrites? Or is it when I have Nitrates but still some Nitrites, and if so, how many Nitrites? Does the ammonia have to be zero as well?

I was looking for some specifics. There are fishes lives at stake!

 

[astroguy]

At the end is, as tkos mentions, when ammonia is 0ppm, and nitrite is 0ppm for the first time. Then add soon your fishes as the bacteria will soon die (unless you keep on giving pure ammonia). If you add too few fishes, that's no problem because the unnecessary bacteria will die but the necessary load will not die. After that you should add fishes only slowly (1-2 fishes at per 1-2 weeks), and the bacterial colony will grow without too high an ammonia peak. If, instead you add after the cycle too many fishes, you will soon get a new peak of ammonia and the tank will begin a new cycle!

So, in brief, better add too few than too many fishes.

 

[Orca]

Thanks tkos.

 

[Allivymar]

Actually depends on how much ammonia you use; I discovered 2-3 drops of pure ammonia a day in a 10g tank cycled the tank to take a decent bio-load (small school of neons, a couple of dwarf gouramis). Using the dead shrimp method does work, but its not quite as controlled (one doesn't know exactly how much ammonia is being given off).

Also, with the pure ammonia method, you know exactly how much ammonia to keep adding until you find your fish; sometimes the fish you want aren't available and you'll want to keep feeding the nitrifyng bacteria until the fish enter the tank. Lastly, a big water change prior to adding the fish is suggested (I did 50-75%).

 

[Orca]

Thanks Astroguy & Allivymar.

Sounds like I should go for the pure ammonia method. Might be a dumb question, but is pure ammonia difficult to find?

 

[astroguy]

no, you can buy pure ammonium hydroxide concentrate (generally 28-30%) from several places on the net. Or you can use good old detergent BUT (and I STRONGLY stress the BUT) make sure that there is no foam, etc, because it WILL kill your bacteria and later your fishes. Look on websites about the fishless cycle about what kind of detergent to use. Good luck.

 

[Enki]

I got mine at ace hardware. The 'janitorial strength' is pure 10% ammonium hydroxide solution and a gallon is under $5. keeps the front of the aquarium sparkling clean as well.

 

[Allivymar]

Yep; grabbed mine from the supermarket. Just get the bottle that contains ammonia only, and no additives.

 

[Orca]

Thanks very much everyone. I'll let you know how it goes.