ORP Level

[hijkim]

ORP

I have question about ORP in Reef Tanks. Form what I hear adding O3 to water raises the ORP and make the water clearer but from my experiment ORP is low in new clean salt mixed RO/DI water and it is high in old dirty tank water.

I do not use Ozone but I wanted to know the ORP level in my tank water and bought Hanna’s pHep5 Ph/ORP meter. The ORP level used to be 270 or so in old tank water but every time I do water changes it drops to about 143. I do one water change per week with about 7 gallons of fresh salt water made with Instant Ocean Salt. But every time I miss a water change and leave it for two weeks the ORP goes up real high and soon as I do a water change it goes way down.

Am I missing some info here? I read several articles on adding Ozone but something like this was not mentioned anywhere.

I just wanted to know that my experiment was correct.

Thanks

 

[DonW]

Here is some reading for you, your testing methods are not valid.
http://www.reefkeeping.com/issues/2003-12/rhf/feature/index.php

Don

 

[Boomer]

That Hanna meter belongs in the garbage can, as it is about worthless. The ORP of new seawater is around 220-270 mV ORP. It takes time for ORP to build, it is a very complicated issue.

I see you have ben to our chem forum on RC, so you should have all the answers you need.
.

 

[dnjan]

Do you aerate your newly-mixed saltwater? I could imagine that if your RODI water has very low disolved oxygen, your ORP would test low. In your tank, however, a skimmer should tend to keep the disolved oxygen higher.

 

[hijkim]

Yes, I aerated the water the day I changed and tested for ORP but I only aerated the water for couple of hours. I don't usally aerate my new salt water but I thought the samething too but the level did not go up.

I think may be when the water is clean water does not need O3 so the ORP is low but when water gets dirty water(H2O), in some chemical reaction, produces O3 to make it self cleaner. Just my thought...

 

[DonW]

Yes, I aerated the water the day I changed and tested for ORP but I only aerated the water for couple of hours. I don't usally aerate my new salt water but I thought the samething too but the level did not go up.

I think may be when the water is clean water does not need O3 so the ORP is low but when water gets dirty water(H2O), in some chemical reaction, produces O3 to make it self cleaner. Just my thought...

Dirty water does not produce the third molecule making itself 03.

Don

 

[Boomer]

Not buy a long shot Don

kim
O3 makes any water clearer no matter how clear you think it is. Dirty water does not necessarily mean low ORP. Clear new seawater has a low ORP.