Honestly I just picked one and payed for it there must have been 50+ on eBay so I will have to wait till it arrives to know which one i purchased as I can't remember
Sometimes I will use a TDS pen when wanting to know does a tank need a wc right now or can I leave it a bit longer. Does save doing those Nitrate tests especially if there are several tanks in question.
guess that may depend on what is in the tank, eg fry, juvs, adults or adults that you are trying to get to spawn. i try not to go over 350 tds generallt but lower in breeding tanks.
It does depend on what your regular water readings usually are. I use all rainwater plus buffers. If my tank go's a fair bit over 200 I do a water change. If its still sitting under 200 and my ph is stable I will leave it.
How accurate to people find the digital PH pens?
I just got one on ebay for only $15 on ebay from an aussie seller and am wondering if anyone else has used them? The same models have been sold on here too