I wouldnt trust the 4dkh on ebay, ive had a few and at least one was useless... think i paid a fiver for 100ml of tap water lol. Jags works well but does need more reagent as very pale once green and hard to see. I also have a couple of reagents that are orange and work well but if it doesnt go blue as soon as added to 4dkh then something is wrong with the water. Personally mine stays green also just different shades of green from co2 on/off, yet to see it go blue again unless i take it out of the tank for 5 minutes.
