use of ozone . good or bad?

[vince]

hi everyone. i have just got an ozone set up for xmas for the pond. it says the recommended setting should be 300mlv but would it be ok to run at at 200mlv? that last thing I want to do is have sterile water that the fish can not cope with. it is just that when using PP you should keep it at 4mlv for 4 hours only.

thanks for looking
vince

[Manky Sanke]

Vince,

I've seen ozone used to great effect to ensure that water is biologically sterile in swimming pool installations because it raises ORP levels and is therefore a powerful oxidiser but ozone isn’t particular about what type of organic cell it oxidises and will destroy whatever cell it touches. This is why, when ozone is used to sterilise swimming pools, great care has to be taken to draw water out of the pool, sterilise it in specially designed equipment, and then remove all trace of ozone from the water before it is returned to the pool. This ensures that ozone cannot escape into the pool itself and affect the eyes or other delicate tissues of bathers.

I have no worries about the use of ozone as a steriliser for pond water if it’s treated outside the pond and every trace of ozone is removed before the water is returned to the pond but this another case where I advise caution. If ozone is used in the pond itself at too high a level, it will damage fish cells (especially gills) with the same efficiency that it damages other organisms. Fish have natural systems that replace dead or damaged cells but subjecting them to continuous high levels of ozone means relying on their self-repair systems being able to replace cells that are being damaged as quickly as the damage is occurring. Also, consider the effects of ozone on your biological filter. If it is concentrated enough to kill off harmful bugs, then it is concentrated enough to kill biofilter bugs.

Ozone is really easy to remove from water by sending it through a small tank with heavy aeration in it as it's returning to the pond. If ozone is used in the pond itself I would rather it be controlled by an ORP device that will prevent the ORP level from going too high. To me, this is safer than the blunt instrument of following a manufacturers' "let's make it seem really simple" advice of setting the generator output to a particular level and everything will be fine. This relies on the fact that ozone is so unstable that it has a half life in water of only minutes. In an average pond, the ozone concentration will halve in about 20 minutes so, in theory, the generator output can be set to a value that will keep topping up the value at the same rate as it is reducing due to natural degradation. But that's for an average pond at an average temperature so how do users know that the ORP in their particular pond isn't being topped up just a little faster than it's reducing and is therefore slowly getting higher and reaching a value where it begins to affect the fish?

Using it outside the pond or in conjunction with an ORP controller is far safer.

I hope that doesn't seem too negative about your Christmas present, why not post a picture of the Christmas woolly that Santa bought you and I'll try to be a bit more positive about that?

[vince]

thank you so much for the reply . the set up is this one http://www.absolute-koi.com/prod2100.html. my main worry was the ozone been mixed in the tube and going straight back into the pond even using a 2m length of pipe work. your idea of having it run into a large box and having some air stones in sounds like the better way. so run the mixing tube to the filter box with the added air in the water before returning to the pond is the way I will go. thank you for the idea manky

[Duncan]

vince
if you want to have a play with ozone I have around 4 bare bones units for sale that produce each 4gm o3 per hour which is a lot so you will have to control it

dunc