ORP after water change

[kevin_e]

My ORP sky rocketed after a water change and has stayed steady. I also a decent amount of live rock from the sump that had a sulfur like smell to them. I'm guessing it may be related to that? And is this a good response by my system?

 

[Randy Holmes-Farley Verified Community Expert]

ORP often drops due to a water change from, presumably, low ORP ferrous ions and related trace metals in a more reduced but more soluble form in the mix.

IMO, ORP is typically not much of a gauge of health in a reef tank, but sulfur (hydrogen sulfide) smells are undesirable and potentially toxic, and removing the source would both raise ORP and be good for the tank.

 

[Pacmann84]

ORP often drops due to a water change from, presumably, low ORP ferrous ions and related trace metals in a more reduced but more soluble form in the mix.

IMO, ORP is typically not much of a gauge of health in a reef tank, but sulfur (hydrogen sulfide) smells are undesirable and potentially toxic, and removing the source would both raise ORP and be good for the tank.

Sorry not trying to high Jack the thread. But I’ve been concerned in the last few weeks. My ORP has been getting to 460 and hanging out at that level all day. There is so much conflicting data and lack of knowledge on my part. I read the R2R where is said that 650 would kill bacteria. I don’t know if I should worry or not?

 

[Randy Holmes-Farley Verified Community Expert]

Sorry not trying to high Jack the thread. But I’ve been concerned in the last few weeks. My ORP has been getting to 460 and hanging out at that level all day. There is so much conflicting data and lack of knowledge on my part. I read the R2R where is said that 650 would kill bacteria. I don’t know if I should worry or not?

High ORP is never a worry if you are not dosing oxidizers like ozone because it never gets too high, ever.

ORP can appear to rise as a probe grows algae on it (or otherwise gets dirty).

In general, there is nothing you should do about an ORP reading unless using something like ozone.

 

[Pacmann84]

High ORP is never a worry if you are not dosing oxidizers like ozone because it never gets too high, ever.

ORP can appear to rise as a probe grows algae on it (or otherwise gets dirty).

In general, there is nothing you should do about an ORP reading unless using something like ozone.

Great. Thank you! I can sleep again lol!! It’s been driving me nuts the last week.

 

[Randy Holmes-Farley Verified Community Expert]

Great. Thank you! I can sleep again lol!! It’s been driving me nuts the last week.

You're welcome.

Happy Reefing.

 

[kevin_e]

Looking at my APEX again after dosing nitrate for the first time (used your suggestion on a 0.8 ppm solution Randy), my pH dropped by 0.04 ppm in 1 hour at peak light cycle. ORP dropped by 15 units in that same time span. Not a concern, just curious about the reasoning.

How quickly should nitrates become detectable in an aquarium after dosing? I would think within a couple hours....unless demand is instantaneous.

 

[Randy Holmes-Farley Verified Community Expert]

Nitrate is instantaneously detectable if you dose it as nitrate.

I don't know why the orp dropped. Lots and lots of things can impact orp.

 

[kevin_e]

Nitrate is instantaneously detectable if you dose it as nitrate.

I don't know why the orp dropped. Lots and lots of things can impact orp.

I dosed to my target level (8 ppm) with potassium nitrate, as I have read you suggest in other threads, but I still am reading 0 on my Nyos. Do you think it was used up that quickly? I waited about 2.5 hours between dosing and testing.

 

[Randy Holmes-Farley Verified Community Expert]

I don’t know, but it is possible it got taken up by organisms with a pent up demand for it. Many folks find demand drops after dosing for a while.

 

[kevin_e]

I don’t know, but it is possible it got taken up by organisms with a pent up demand for it. Many folks find demand drops after dosing for a while.

Thank you. It turns out I wasn't paying close enough attention to what I was calculating. But I will keep an eye on demand drops as I have determined that my tank has been nutrient limited for over a year (recently identified golden algae that I chalked up to nutrient overload. Ignored my tank hoping it would cycle out. A year later, same issue. I assumed my "0" readings were from consumption). Anyways, I was calculating each 1 ML solution as a 0.8 ppm increase when it should have been 0.08 ppm increase. So 8 ML wouldn't show me any changes on my kit.