Cycling with RO/DI

[Abemas]

I should be starting to cycle a tank in the next few days and I'm planning on using RO/DI water. Any additional steps I should to take/avoid because of the type of water used? I'm thinking I may need to seed the tank with some bacteria from another tank. Any advice?

 

[cmor1701d]

I'm pretty sure that RODI is not recommend for FW tanks. RO maybe, but even that will need to be balanced somewhat before being used.

 

[Abemas]

Aha! I guess I should have done some reading before I asked that question. From what I can tell RO is fine to use for FW but I'll have to add some dissolvable solids back to the water after the fact. Am I on the right track?

 

[BigJim]

You're on the right track. Buffers need to be added to RO water to prevent pH swings.

 

[mfdrookie516]

Why are you using RO/DI, or even RO? Unless you're stocking very sensitive fish like discus, there's really no need for anything other than tap water and a good dechlor like prime.

 

[Abemas]

Why are you using RO/DI, or even RO? Unless you're stocking very sensitive fish like discus, there's really no need for anything other than tap water and a good dechlor like prime.

Well I haven't used anything yet technically as I'm just planning at this point yet =). I guess I assumed RO would simply be better than using tap as it allows me to start from a clean slate. We already have a unit for drinking water so I figured why not. Will it really be more work going RO than tap?

 

[Ziggy953]

I learned the hard way as well, coming from SW to FW I thought water should be perfect as well. What I have done is to take my RO/DI unit and rather than save the RO/DI water I collect the waste water and treat it with prime. As a result of this my plants are growing like mad. I know it seems like a bit of a waste but to grow plants in a FW system you need all those elements and nutrients.

It's working well for me.

 

[BigJim]

Interesting approach Ziggy. Have you measured the nitrates in the waste water? Sounds like a good way to concentrate the good stuff for plants.

 

[Ziggy953]

Interesting approach Ziggy. Have you measured the nitrates in the waste water? Sounds like a good way to concentrate the good stuff for plants.

I have not measured nitrates in the tank. Being a FW planted system I'm not that concerned with the nitrate levels. I can say that my little 10g tank has had so much growth that I have to remove plants so the fish can swim.

 

[jsoong]

Well I haven't used anything yet technically as I'm just planning at this point yet =). I guess I assumed RO would simply be better than using tap as it allows me to start from a clean slate. We already have a unit for drinking water so I figured why not. Will it really be more work going RO than tap?

I would test the tap water & see what it is like before going the RO route. Pure RO needs to be reconstituted with buffers (& ferts & traces if you are growing plants) before use, and that needs to be consistent with each pwc, so it is more work & also more chance of errors. Unless your tap water is really screwy, using plain tap is the way to go.