How to use hm com-100 TDS meter with organic

Hi everyone. On a past forum post a kind member suggested checking my nutes ppm to help with feed levels as I was having trouble with my autoflower. The problem is I am using biobizz nutes and have read it’s not possible to measure which I find hard to believe. Does anyone have a com-100 and if so which scale should I use if at all. Or have I just blown £70 on something that won’t help me at all. I’m growing in Batspecial mixed with biobizz light mic by the way.
 
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