What kind of strange water do I have?

whoa the test kit i uses says that you add test liquid one drop at a time until sample turns yellow where are you reading that you keep adding until it turns green??????????????????????????????????

Do you have the KH/GH test kit from Aquarium Pharmaceuticals? http://bit.ly/h1m7UY For GH the color is supposed to turn from orange to green.
 
My 2 - 3 year old planted tanks have nitrate readings of about 5 - 10.

I really hope the OP can identify and solve the problem before buying any more fish, if this has been going on for several years.

Well I've been doing 25% water changes every few days and then a week apart and things seem to be ok right now at least for those fish still remaining (5 neons, 3 honey gouramis, and a panda cory). Lost the other panda cory last week though. Also scraped off a lot of the algae around the tank and trying to suction up as much organic matter off the substrate as possible whenever I do a water change. I think my nitrifying bacteria were a bit out of whack cause when I first started this thread I was starting to get slightly elevated ammonia levels (5-10) but now that's back down to 0 after I started adding Stresszyme after water changes. Nitrate is starting to show up at around 5 though. I still need to trim off some of my more algae-covered crypts and dead java fern leaves but hopefully the worst is behind me.

I'll probably keep an eye on it with just the current inhabitants for another month before trying to do anything else with it.
 
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