Best DO tester on the market

[Ben]

I would like to test and learn more about dissolved oxygen in the aquarium.
Does anyone use one or have used one in the past.

Something we all take for granted when keeping fish, yet very important!!

Sera have one, are they any good?

[Merrilyn]

This could open up a whole new conversation area Ben.

I'm very interested in how to increase the amount of dissolved oxygen in the water, especially at times when fish are under stress. And no, I don't mean just adding extra airstones LOL

Some kind of reliable test would be good.

[samir]

probably a CO2 setup with an oxygen cylinder. some links that may be useful.
http://www.enviroequip.com/sales/DO600extech.htm
http://www.ferret.com.au/articles/87/0c02ff87.asp
http://schools.fcps.org/outdoor/oxygen.htm
http://www.ausetute.com.au/waterana.html