I'm sorry, but this isn't a cheap hobby if you want to keep corals. Particularly some LPS and definitely all SPS. I have been in it for 12 months now, went in with my eyes open but are still happy I have deep pockets. I found the initial expense is in two parts - the initial investment in equipment and the second investment in time and money to make and learn from mistakes. I am hopefully over that now and the ongoing running costs won't be too much. I am still a wet behind the ears 1 year old reefer however.
Good equipment costs quite a bit but pays back in time and money in the long term. Good quality consumables (test kits, salt, additives) also cost money but pay back in reduced (but not zero!) problems.
It sounds like your test kits are not good enough quality (API?). I initially used them for Phosphates and Nitrates but found they were nowhere near enough for what I needed, so I now use Red Sea kits. I did use Red Sea kits for Alk, Ca and Mg initially as I knew I needed good quality ones, but didn't realise at the time I needed to know PO4 and NO3 better. After that mistake (which cost me a Torch like you) I learnt. My target range is ~0.02 ppm PO4 and ~1 ppm NO3. API can't measure that low.
You also need to measure regularly to get to know the "˜feel' of your tank. If you aren't dosing with a dosing pump this is even more important. I dose with an Apex and test at least weekly, twice when I can particularly when I am adding to my tank, or something is not going swimmingly. This is on top of the 24x7 tests the Apex gives me. Many reefers I follow test even more often.
If you want to be successful at corals I'm afraid you need to invest more time and money in test kits, dosing solutions and other items. Do what I did and read as much as you can. Also ask questions in the forums, but do your research first. I personally don't want to waste the time of all the helpful experienced reefers we have on these forums with dumb questions I could answer myself with a little bit of effort and research.
If the investment is beyond your means at the moment then I suggest you stick to FOWLR and a few hardy leathers and then branch back into more delicate species once you do have the time and money to do it right. Whatever you do, good luck.
Regards, Brad.
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