because the one you have reads faster more accurate and have auto temperature compensation. My hanna meter which reads ph/tds/temp and has a unique feature called cal check make sure my meter is well calibrated accurately, plus its water proof.
i got 1ft plants in 4x4 cube flowering and they only need to be watered every 24 hr, i turn it on for 15 min. depending on the gph pump you have turn on the pump time it when it finish flooding then give it another 2 min to soak up everything and turn it off and you have your time to flood.
it should turn purple on its own without needing the temps to be low. i've never grown gpd before but i have seen purple strains turn purple in high temps.
yes, if you don't have auto temperature compensation then you need to take the temperature of your calibration fluid also and work with the chart that is on the calibration fluid, or 25c at 7.0 or 7.01 depending on your calibration solution.
sorry about your bad experience with them, i've always thought it would have been better to order st8 from hydro stores and such. But use the test stripe my hydro store guy told me that those are more accurate then the digital meters. GL! btw blueberries are sensitive.
should be the same, altho i don't stay up there most of the dro in the south comes from canada or northern states and regular dro has always been the same for me 2-3 yrs now. Sometimes there will be a price drop but that's only due to top dogs trying to make a quick buck but it doesn't last...
oh and rockwool holds alot of water, its like a sponge almost but holds more water then a sponge. I ussually water my seedlings every 3 days, as it grow i increase, now im watering a 2 ft plant in a 4x4 cube once a day.
yes you would have to go with rockwool, it will be like soil except you cannot let it dry out. Feel your rockwool to know when you have to water, bigger plants suck up more water so the bigger the plant the more you have to feed.