orp ?'s

[mtc1966]

so i found out water changes make the readings go down. my question is why when you are putting in fresh clean water?
also does the orp readings go down when lights come on ? why?
thanks

 

[Randy Holmes-Farley]

ORP is not a measure of the cleanliness of the water, contrary to popular belief.

New salt water often has a low ORP, probably just because of the mix of reduced metal ions in it (like iron as the ferrous ion) relative to more oxidized ions (like iron as the ferric ion).

pH also has an impact on ORP, and that is probably the light effect you observe.

This has more:

ORP and the Reef Aquarium
http://reefkeeping.com/issues/2003-12/rhf/feature/index.htm

 

[mtc1966]

thanks Randy

 

[Randy Holmes-Farley]

You're welcome!

Happy Reefing.

 

[Bojan]

In most of the reef aquariums, i found that ORP go down with water changes.

I have graph of ORP and it is usefull to have information, when I made water changes.

ORP in my aquarium is approx 310mV, when I change 5% of water, ORP decrease to 280mV and than raise linearly to 310mV in the next week.

it is quite similar in aquariums of my friends, who have ORP metering and no ozone dossing.

 

[Bojan]

I found some information that Fe have to dosed constantly, because Fe very quicly react in the sea water. Is this in some correlation with ORP decrease, when we made water change(I belive that there is Fe in fresh Sea water mix) ?