I'm hoping someone can help me with this. Two days ago I took a water sample in to the one pool store in the area who is supposed to do accurate water testing. I wanted to have it tested for metals, since I can't test that.
The test results were so vastly different than my numbers with my Wal-Mart drop kit, that I am really unsure which is accurate.

My TA is still high ~ tests in the 320-340 range at home; the pool store test showed 210.

My CYA tested 25 last week, theirs showed 0.

When I test for hardness, the kit says that when I add the hardness indicator, the water should turn red if there is any hardness. My water turns a very slight yellow-tinted clear. The pool store test says my hardness is 367.

Their test showed no iron and .2 copper, even though I know that the water I top off with is high in iron and I had overdosed it on copper algaecide about 3 weeks ago. I have put a sequestering agent in 3 times since then. Would this account for the test showing no metals?

Also, when I use the dilution method to test my CL, I don't seem to get accurate results either. I am using reverse osmosis water, rather than distilled to dilute with. Would this make a difference? When I test without dilution, my color is deep yellow - almost yellow-orange. But when I dilute and multiply, it comes out to 6-7 ppm, which I know is not correct. What am I doing wrong?

Thanks for any help!