Cycle new tank by using another tank


New Member
Hi guys,

i have recently bought my second tank (jeej!) and yesterday i set it up. As i am very unpatient, i want to go thought the nitrox cycle as fast as possible. Therefore i have taken some steps to make sure the tank has a good kickstart, but now i am a little unsure as to how far in the proces the tank is. could you guys (and girls) give some advise in how to best proceed from here?

This is the situation:

As i said before i wanted a second tank as addition to my 21 gallon community tank that i already have. I decided i wanted to have a shrimp tank (with some small nano fish) so i bought the Fluval Flex 15 gallon. To kickstart the new tank i took the following steps:
  • I bought te plants a week before the tank, stored them in a filled bucket with a heater and lights. I threw some fishfood in the bucket to let te water become 'dirty' with ammonia, nitrite and nitrate. i let that rest for about a week while i orded the tank, and used the water from that bucket (2,5 gallon) to partually fill the aquarium ones it was ready.
  • I also dropt a clean sponge in my old aquarium on a place where there is strong current. i let that sit there for a week and dropt the sponge in the new aquarium once it was filled.
  • Furtermore, i took the filter out of my old aquarium and squeezed it into the new aquarium. I was quite dirty as i did not clean it for a few weeks. water was properly clouded after it.
  • i added some fishfood and a bacto turbo starter and water conditioner to the water.
  • there are quite a few fastgrowing plants and mosses in the new tank
  • The fluval flex has quite a big filter compartment and also has a 'spare' compartment. i used extra filterfoam to fill most of that extra space in the back.
as you can see, i did quite some things to make sure there are plenty of bacteria in the new tank. after these steps i waited 24 hours. Now i am curious to what i should do next. On various places on the internet i have read that it should be fine to just put fish in (shimp wil come later, when the tank is more stable). But while i am inpatient, i do not want to harm my fish by putting them in an uncycled tank.

What do you think? can i put fish in the tank, and if so, how many (i can just take them from the old tank, so don't have to buy them)?

Water parameters:
CL = 0
PH = 6.5
KH = 6-10
GH 7-14
Nitrite = 0 (mg/L)
Nitrate = 25 (mg/L)


Well Known
Well, the fish food should act like an ammonia source to feed the bb. Aside from that there was no real reason to get the plants before the tank. The biggest possible issue I see is the tank not having a strong enough cycle when you add fish. You can still add them, just keep an eye on the paramaters to make sure you don't get an ammonia or nitrite spike.


Active Member
You have taken proper steps but how long has the tank been cycling? I know how hard it is to wait but I would make sure that the tank is cycled well before putting anything in it. You said you don't need to buy them because they are already in your other tank so what exactly is the hurry? If you are dosing with fish food for the BB how much are you putting in and can the BB get rid of 1ppm of ammonia in a 24 hour period?

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