Lets talk about ORP

[lilrobb]

Gotcha,

the problem I foresee is, "clear" is not really a good measure neither, as water cannot get clearer than clear.
Unless I misundestand and you only occassionally turn the ozone on and clear the water.
What I am saying is, if the water is "clear", am I really applying the lowest needed dose or am I already overdosing?

 

[mojo]

LilRobb;601033 wrote: Gotcha,

the problem I foresee is, "clear" is not really a good measure neither, as water cannot get clearer than clear.
Unless I misundestand and you only occassionally turn the ozone on and clear the water.
What I am saying is, if the water is "clear", am I really applying the lowest needed dose or am I already overdosing?

Define "needed dose". What do you hope to accomplish with ozone? If it's clearing up the water, then that can be done visually. If you're looking to do something else, then you'll have to come up with some way to test it, and an ORP reading is a horrible indicator of that. I'm not aware of anything else you could test against, but that doesn't mean there isn't anything.

Think of using ozone like using bleach to clean something in your house. A little goes a long way. You could use it at 100% ratios and you're guaranteed to clean the surface, but you'll have to deal with the fumes and chemical burns (ask me how I know... :doh. An ORP reading may be equivalent to an electronic reading of the residue left on your cleaned surface; the two are definitely related, but may not be the best indicator for overall usage.

Not sure if that analogy worked...

 

[lilrobb]

Good analogy!
I'll try again (have a hard time wording this).

Let's assume water turns yellow when in dirty, clear when perfect and blue when overdosed with ozone. (I know it doesn't...)

This would be easy to calibrate the output

if yellow = more
if clear = good
if blue = less

But since water doesn't turn blue or shows any other signs of overdosing - how do I know I accomplished my goal (clear water) without having overdosed?

 

[mojo]

LilRobb;601037 wrote: But since water doesn't turn blue or shows any other signs of overdosing - how do I know I accomplished my goal (clear water) without having overdosed?

I know it's somewhere here on the site, but the "Mojo bucket test" goes like this:

Use a while salt bucket - the 5g type. Remove 5g of water from your tank into the bucket (ideally from mid-water column, to avoid dirt, etc). Literally look in the bucket. With no ozone, the water will have a slight yellow or green cast. You may not notice it at first - it's pretty slight.

Start turning up the ozone slightly. Go by 10mg/hr or whatever - just use a small, consistent rate. Check daily, and go up by another unit the next day if there's still a yellow cast in the tank water.

When you stop seeing the yellow cast, stop changing the ozone. It actually does have a slight blue look to it when you're good to go! (Contrary to popular misconception, water is very slightly blue. Seriously.)

The other method, if you have a longer tank, is to put a white sheet on the far end of the tank and look down the length at the paper. Same thing- you're looking for the color change.


By using that method, you use only what is needed for your tank, and not the horribly high rates quoted by ozone unit manufacturers.

 

[lilrobb]

10-4,
I missed the "check daily" part, and with "turn-up" though of something more drastic than 10mg/h...

Clear now - maybe it's because it is monday...

Thanks for the thorough explanation, Mr Prez!

 

[mojo]

LilRobb;601042 wrote: 10-4,
I missed the "check daily" part, and with "turn-up" though of something more drastic than 10mg/h...

I run my 800g system with ~100mg/day. Of course, it really depends on your bioload level, but I wouldn't call mine "low". You can choose whatever increase rate you want, as long as it's incremental.

Thanks for the thorough explanation, Mr Prez!

That's why I get paid the big bucks! Oh wait...

 

[acroholic]

Chris,
Do you inject the ozone via your skimmer or a reactor?

 

[mojo]

I use my skimmer. And I don't bother with carbon filtering out of the skimmer....

 

[ichthyoid]

Robb-

ORP is the net result of all of the oxidation and reduction reactions in a system. In effect, it is an indication of the availability of electrons for chemical reaction.

FWIW-RedOx reactions is one of the chapters that usually kicks everyone's butt in freshman chemistry (not mine ).

Randy Holmes-Farley wrote a pretty comprehensive article on the subject, so I posted it below.