Test if it is possible to explain the know ORP reduction when adding H2O2 into a saltwater

[Randy Holmes-Farley]

We also got and still get some remarks that ORP drops after water changes with Tropic Marin salt. I always suspected this to be a reaction to increased bacterial activity which I ascribed to the addition of fresh trace elements.

ORP drops after water changes with many/most salt mixes. It is also very low in the new salt water.

I always attributed this to the use of the reduced forms of metals in the salt mix because they are more soluble, such as iron Fe++ vs Fe+++.

 

[Lasse]

New electrode - it is calibrated but shows around 550 mV - no dip to talk about Red addition of 5 ml H2O2 at 19.30. It is 5 cm apart from the old electrode. Can´t combine the charts because a bug in the GHL chart program (will not use the same y-axel

Old electrode red 10:30 addition of 5 ml H2O2

NOTE - the axes are different New electrode - 552-588. Old Electrode - 100 - 400 mV

Huge impact

In MY case - it seems that Hans Werner is on the right track. The good thing with this is that I can let this electrode be in my tank for a while and redo the addition after one week/ two weeks and so on. If it is a biofilm question - the new electrode should act as my old after a while. We test tomorrow again

Sincerely Lasse

 

[Rick Mathew]

New electrode - it is calibrated but shows around 550 mV - no dip to talk about Red addition of 5 ml H2O2 at 19.30. It is 5 cm apart from the old electrode. Can´t combine the charts because a bug in the GHL chart program (will not use the same y-axel

Old electrode red 10:30 addition of 5 ml H2O2

NOTE - the saxes are different New electrode - 552-588. Old Electrode - 100 - 400 mV

Huge impact

In MY case - it seems that Hans Werner is on the right track. The good thing with this is that I can let this electrode be in my tank for a while and redo the addition after one week/ two weeks and so on. If it is a biofilm question - the new electrode should act as my old after a while. We test tomorrow again

Sincerely Lasse

Lasse: What if you soaked the "old" electrode on H2O2 for a period of time...Clean it off and compare the results to the performance of the old probe before soaking...Just a wild and crazy thought.

 

[Randy Holmes-Farley]

I'm not convinced the idea that Hans Werner suggested that it is increased O2 from the peroxide that causes the biofilm to react in a way that lowers ORP under the biofilm. That explanation lacks plausible mechanistic details, and doesn't seem that likely to me. Possible, but not likely, IMO.

 

[Lasse]

When it has stabilise itself - and I get the same result (if I get it) from both electrodes - I will clean the old and sterilize it with 45 % ethanol. But before that - I will change ports between the old and new electrode and see if it differ in result. This have to be done well and properly. I must - as far as possible - be able to exclude incorrect use and / or incorrect equipment - otherwise there is no chance to convince anyone.

This experiment have not gone that way I expected.

Sincerely Lasse

 

[taricha]

I'm not convinced the idea that Hans Werner suggested that it is increased O2 from the peroxide that causes the biofilm to react in a way that lowers ORP under the biofilm.

One clue against oxidation of organics by H2O2 as the cause might be the rate of the observed change in the ORP measure.
Analogy (that may or may not apply): when I measured ORP while chlorinating samples with bleach, responses due to chlorinating ammonia or added metals was very fast - seconds. The response to organics (proteins) was much slower - minutes.

I think the times I've seen people post their ORP drops from peroxide it's nearly instant.

 

[taricha]

It is 5 cm apart from the old electrode.

Which one of those am I supposed to be suspicious of?

 

[Lasse]

ORP drops from peroxide it's nearly instant

Yes - It less than a minute - even when I dose in the DT and the probe is in the sump.

Sincerely Lasse

 

[Lasse]

Which one of those am I supposed to be suspicious of?

The new acts rather weird - high reading and very unstable. But this is the way it is normally when I change an redox electrode. It will normally take a week or two before it stabilize itself. This indicate either that it will take a long period before internal fluids and external fluid have stabilize the whole thing or - that a biofilm must be build up first and that you measure the redox potential below the biofilm as suggested. We will see - I have more electrodes

Sincerely Lasse

 

[Lasse]

I switch the redox port (calibrated too) and I did a 5 ml dose this morning - same result as last evening - huge difference with the old - nearly no difference at all with the new (new port)

Sincerely Lasse

 

[Hans-Werner]

I'm not convinced the idea that Hans Werner suggested that it is increased O2 from the peroxide that causes the biofilm to react in a way that lowers ORP under the biofilm.

Maybe not, maybe another reason, but I think it is worth to check for biofilm effects.

The biofilm may also enrich trace metals, especially in the alginate matrix etc., a lot of things we can only speculate about at the moment. But not always things are straightforward, sometimes they are a bit ... complex.

 

[Lasse]

New electrode - very unstable as you can see Red = addition of 5 ml H2O2. Sample period 1 min

New electrode Red = addition of 5 ml H2O2. Sample period 5 min. Of some reason did the samplecollection do a 30 minutes jump exactly when I dose - it looks like the reaction is happen before the dose - but it was in reality 1 minute after the dose

Sincerely Lasse

 

[Rick Mathew]

When it has stabilise itself - and I get the same result (if I get it) from both electrodes - I will clean the old and sterilize it with 45 % ethanol. But before that - I will change ports between the old and new electrode and see if it differ in result. This have to be done well and properly. I must - as far as possible - be able to exclude incorrect use and / or incorrect equipment - otherwise there is no chance to convince anyone.

This experiment have not gone that way I expected.

Sincerely Lasse

I know the feeling!...Some of my experiments don't come anywhere near my expectations...It is confusing!!...When I am confused I know I am about to learn something....I guess that is why they call them "experiments"

 

[Frostynipps]

what does orp stand for anyway. I'm new

 

[Randy Holmes-Farley]

what does orp stand for anyway. I'm new

Oxidation Reduction Potential:

ORP and the Reef Aquarium - Reefkeeping.com

 

[Frostynipps]

Oxidation Reduction Potential:

ORP and the Reef Aquarium - Reefkeeping.com

thanks

 

[Randy Holmes-Farley]

thanks

You're welcome.

Happy Reefing.

 

[Frostynipps]

I know this is about orp experimenting but will H202 make your tank crash? what is tank crash? I'm dealing with red bacteria cryno, dosing at night 4ml for 32 gallons and a kessil 360x set to all blue all the time at 5-15% intensity.

 

[Frostynipps]

I wanna be a reef chemist but I'm not that smart so I'm trying to go to school to become a marine biologist.

 

[Randy Holmes-Farley]

I know this is about orp experimenting but will H202 make your tank crash? what is tank crash? I'm dealing with red bacteria cryno, dosing at night 4ml for 32 gallons and a kessil 360x set to all blue all the time at 5-15% intensity.

Some folks dose it. Too much will certainly crash a tank. I'd search on cyanobacteria and hydrogen peroxide to see how much folks use and when and why.