Iron and Ozone

[Miami Reef]

I inject ozone into my skimmer once a week.

How long after closing the ozone can I dose iron without worrying about it converting to ferric ion (Fe+++)

I also like to add trace elements once a week, but I’d prefer to do so post-ozone because I don’t want them to change forms.

How much time should I wait after stopping ozone? Are my concerns valid, or should I dose them while ozone is actively working?

 

[Miami Reef]

@Randy Holmes-Farley

 

[taricha]

Are my concerns valid, or should I dose them while ozone is actively working?

You aren't crazy. But I don't know how much ozone changes the calculations.

I expect that reef-relevant doses of ozone or peroxide are sufficient to convert most of the Fe2+ in the water to Fe3+.
Reef tanks oxidize this anyway, but if expect it to be much faster with those in the water.

Why are you dosing Fe and why are you dosing ozone? (I think I know the answers, but better to not assume).

 

[Randy Holmes-Farley Verified Community Expert]

I agree. I do expect any iron passing through the ozone area to become Fe+++. It’s not clear what impact that has. It is less soluble the Fe++, but if bound to organics it may still stay dissolved. Data on which iron forms are most readily used are mixed.

 

[Miami Reef]

You aren't crazy.

Thank you. I’ve been going through a hard time lately, and this oddly made me feel better.

Why are you dosing Fe and why are you dosing ozone? (I think I know the answers, but better to not assume).

I dose iron and trace elements because my tank seems to deplete them based on ICP MS.

I use ozone to oxidize tannins and yellowing compounds for water clarity.

I also want my organics smaller so hopefully bacteria can consume them. It just makes me feel better than I’m doing my best to prevent some organics from accumulating.

I use activated carbon and I recently switched my water change schedule to one large change, once a year with NSW, so I’m not putting all my eggs in one basket by assuming ozone will take care of all my problems because it can’t.

 

[taricha]

I dose iron and trace elements because my tank seems to deplete them based on ICP MS.

I use ozone to oxidize tannins and yellowing compounds for water clarity.

So if I'm adding Fe because I want some organism to get it, then yes - I'm going to space the time out to be well after ozone (or H2O2) has already reacted and done its thing.

Randy pointed out why this is a guess (maybe Fe3+ still is bioavailable), but I think I'd rather not have it all oxidized if I want organisms to access it.