Yes, you could do that if necessary. Just be advised, when I got my TF-100 I did a comparison between all the tests with it and my Wal-Mart kit, and I had slight discrepancies with the TA and CH tests(+/-20ppm on each). However, since those need to be in a range, and not a specific number, you should be just fine.
I'm no expert but, when I found TFP, last summer, I did use the Walmart kit, and the extra HTH reagents I had, until I ran out of reagents and, also, I ordered the separate FAS/DPD from Duraleigh. I did pick up some Taylor CYA reagent from Leslie's as the amount in the Wally kit was so small. I test for CYA more frequently than most people, probably, as I have to backwash more frequently due to our extreme amounts of very fine dust. We also had record winter and spring rain amounts so lots of water had to be let out of pool on several occasions. Then there's the times I over filled the pool, when I was topping up, and forgot the water was running.
I, also, like using the HTH CYA bottle and tube as it uses less reagent than the larger bottle and tube that come in the Real kit. I don't think the Wally kit does Calcium Hardness (CH), just total hardness, so you have to estimate the CH using a simple formula. I think I found that in Pool School.
The Walmart kit won't be as accurate but for me it was close enough until I could gather the funds for the Real Kit. Any kit, with fresh reagents, is better than test strips or testing done at most Pool Stores.
I'm a big fan of the "you get what you pay for" club, and I would rather have accurate test results than have to be guessing. To me, to save a couple bucks, but always wonder if I am really getting accurate info, is not worth the savings.
I have a lot of time and money invested in my back yard, and I am very proud of my water (thanks to TFP!). If I have to forgo an adult beverage or two to continue to get accurate results, then by golly that's the price I have to pay
jeeman - you don't mention what type of pool you have. If it is permanent (real AG or IG) I'd spring for duraleigh's full test kit. If it is an Intex or other temporary/seasonal pool, I'd guess you will be able to go all season with only the FC/CC kit from duraleigh since your HTH has the OTO and pH and also enough for several CYA tests. Duraleigh does sell a CYA kit too, so if you run out of that you could buy that kit and it would likely last a couple years.
Thanks for the reply. I have an in-ground plaster pool, 10k gallons.
I've just been having a hard time trying to keep the algae from growing. Whenever I throw in shock, it seems to do ok for a week or so. I'm guessing I must have high CYA. If so, I'm going to get it in the 30-60 range and then start using bleach. I haven't tested it yet because the pool pump is malfunctioning....I have had stagnant water for 4 days now. The pool guy will arrive on Monday, hopefully earlier.
Then I'm going to start the BBB method. I have a bucket full of 3" tablets though....I guess when my CYA gets below 30, I'll throw a tablet or two in there as a way to "condition" the water.
I think I'm just going to spring for the full test kit from TFTK (is that the right acronym, or does everyone use "Duraleigh" here?). Shipping is a flat $10.61 whether I get the $26 FAS/DPD kit or the full $68 kit.