Seeding new tank with old water

[Mr31415]

I know it is a good thing to use some of your old tank's water when upgrading to a new tank when moving your fish - for the bacteria population as well.

My question is - what would be worse: Using old water that is very high in nitrates/phosphates in the new tank or using all new RO/DIwater and nothing from the old tank?

 

[Frick-n-Frags]

the bacteria population isn't as much in the water as you think

it is more on the surfaces of the stuff in the tank.

IMO, a couple scoops of gravel/sand or some of the old live rock
from the old tank is what you want. that's where the bacteria is

 

[jeffbrig]

Very little bacteria is in the water column, so it's not critical from that perspective. If you're transferring inhabitants of the previous tank, it might be easier to start them with some amount of water from the first tank, then slowly fill with new SW. Otherwise, you have to treat them like new fish coming from the LFS, and slowly acclimate them to the new conditions. You can go either way.

 

[Mr31415]

Cool I like that option - acclimating them. I would dread using bad water....

 

[returnofsid]

You'd be better off seeding with some live sand and live rock than old water. The water column itself is pretty useless for seeding tanks.

 

[Mr31415]

Yeah I plan to move all my LR and a couple of cups of old sand over.