Ozone why would you use in a koi pond? It is a strong disinfectant or bacteriacide

Ozone is a most wonderful substance, provided you're not a really small living organism. It is the second strongest oxidising agent known. This means in a nutshell that ozone rushes around like a mad thing, finds something it can attach itself so and oxidises it. By oxidise I mean react with, but in a specific fashion. Ozone can thus be used to supplement existing filter systems in Koi ponds to varying effect.

This is great news. Ozone thus has the potential to wipe out any free floating algae, viruses, pathogens, free swimming bacteria and so forth, reducing itself to beneficial dissolved oxygen in the process! Is this too good to be true?

Well, yes and no. Yes, if you run too much ozone in the pond, so much that it starts getting into your biofilter before being completely broken down - under these circumstances I would think that most of your Koi would already be dead (oxidised!). No, if you run it in appropriate quantities. This is yet another reason why it is important to know exactly your Koi pond volume...

Too little ozone won't do any harm. It just won't do much good either. As with all things there is a balance. To all intents and purposes Ozone is measured in milliVolts - the more ozone there is, the higher the mV reading. The table below serves as an illustration. I sourced it from http://www.ozoneapplications.com

• 0-150 mV ... No practical use

• 150-250 mV ... Aquaculture

• 250-350 mV ... Cooling Towers

• 400-475 mV ... Swimming pools

• 450-600 mV ... Hot Tubs

• 600 mV ... Water Disinfection *

• 800 mV ... Water Sterilization

In water, ozone's half life is remarkably short - from the same site: Dissolved in Water (pH 7) Temp (C) half-life is

• 15 degrees ... 30-minutes

• 20 degrees ... 20-minutes

• 25 degrees ... 15-minutes

• 30 degrees ... 12-minutes

• 35 degrees ... 8-minutes

A half life is the time taken for the concentration to halve. So at 15C, the concentration of ozone after one hour is a quarter of what it was at the start.

I recently installed an ozoniser into my little plunge swimming pool. I have been battling with black algae in the thing since last summer as it stands all day every day in the full sun (nice and warm but forget one cup of chlorine once and you're swamped with algae almost overnight so fast does it grow). I have noticed that the pool water is crystal clear, I don't need nearly as much chlorine and my algae growth seems contained if not actually reduced. But it's still early days and we will have to see how it goes. In principle however, so far so good!

Now, will I be adding an ozoniser to my Koi pond?

I think I will most certainly consider it. It will have to be installed after the bio filter stage, as a final stage of my koi pond filter system (if I put it as the first stage after my bottom drains I would wreak havoc with my biofilters). The appropriate sized ozoniser will have to be considered to develop an ORP level of approximately 250 mV.

More on this to follow. I think the topic is important enough and that ozone can help play a significant role in maintaining koi pond water quality - it has after all been used in major aquariums for well over 15 years alread

 Happy Koi keeping!