oxygen in water (early head scratching)

does anyone ever, or is it possible, or is it worth while to test oxygen levels?

wats the max percentage of oxygen water can hold?

wat is a minimum that would be needed to keep fish?

ah jesus, why do i keep posting in the wrong section, i constantly go on about it. i always say to myself "i will try do it the way folk must do it to see why they do it wrong" starting wit the new topic tab and then i ALWAYS forget to ammend the section.

please forgive me mod and please move it to the correct section and delete this if not to much hassle

LOL - That's ok Dar, I have special alarm bells to tell me there is a post in the wrong category.

Moving the post now

PM Ian, he tends to know wat's wat.

Kev.

stretnik wrote:

PM Ian, he tends to know wat's wat.

Kev.

thats not wat the forum is about, that is borderline rudeness. i want everyone to benefit

Good question, and good point about the use of a forum. I also don't mind PMs.

There's a lot in those few questions.....the last 2 being the more difficult and varied ones.

Is it worth testing the oxygen content of the water?
if you happen to have a decent probe then why not, but I don't think it is worth going out to buy one unless you're trying to run a system at its limits or wish to get into a bit of research.

Yes there is a place for oxygen testing, but I feel it would be wrong to bring it in as something that is a 'done thing' as that takes fish-keeping too much down the line of 'techno-tanks' (and loadsamoney, and even snobbery).

If you're running a massive multi-tank system off a centralised marine system then a few extra quid spend on an oxygen probe might be worth it though for a piece of mind....ie with such a big system, you don't want any mishaps.

How much oxygen will water hold?
we could give a table of temperatures and salinities etc and plot some graphs for each variation of them. The oxygen content varies with various other parameters (such a named above, eg higher temp means less oxygen dissolved).

But there is a more vital measurement.....that is how much oxygen does your tank demand? the answer to that is more complex than a simple set of graphs that can be easily calculated.

The level of oxygen demand will depend upon what is going on in the tank.....eg aerobic biological filtration, decay, microbes in the water, cyclops in the water, non-biological oxidation of waste, and the demands of the fish.
There is a double constraint in there.....eg if the temperature is higher then not only is there less oxygen dissolved in the water, but the metabolism of the fish increase to an maxima (or optimum) and that demands even more oxygen.

Minimum oxygen?....that depends upon the specific fish, the temperature and so on.
Different fish have different oxygen demands, but some can pull out some special tricks. Goldfish are wizards at that (in fact, I can't actually think of another fish that can do what goldfish do).

There is also a maximum oxygen level above which harm will come to the fish......oxygen is, after all, an extremely toxic gas. If we cannot detoxify it rapidly enough we (and any other organism exposed to oxygen) end up with irreparable damage.....and that damage can actually produce a chain reaction that keeps on going causing even more damage (this is all about free-radicals).

Is there any particular water conditions (eg freshwater, marine, cold, warm, high-warm fish) that you are particularly thinking about Dar?

or are you embarking on doing some research on filtration technology?

ian