?'s about water and ppm

My tap water reads at 118ppm and im wondering if after nutrients are added and im going for 800ppm should i have 918ppm or just go to 800ppm on the meter? Also, do you think its still beneficial to let the water sit out for 24 hrs w/ the tap water only at 118ppm to get rid of the chlorine or w/ low ppm does that mean there isn't much chlorine in the water to effect the plants? Any help would be great. Thanks

118ppm is pretty good. IMO the difference between 918 and 800 is small and would probably lean towards 918. But then again your growing method, strain, nutes, ...etc factor in too. Of course you go go conservative and do 800 and see how the plants react going that way. Regarding chlorine...see this thread. BTW, chlorine does not count against ppm readings. Try it out...test your water at tap and then after 24~48 hours...you won't notice a difference.

You dont subtract the ppm of the water & it is beneficial to allow your water to air out to allow chlorine dissipation. I use a chlorine filter so i dont have hundreds of gallons of water adding to the humidity.

Are you sure about that? My tds drops about 10 ppm give or take, over 24 hrs of sitting out. Small amts of chlorine is good for plants and necessary for photosynthesis, but my water is 290 out of the tap.

R1Farmer said:

118ppm is pretty good. IMO the difference between 918 and 800 is small and would probably lean towards 918. But then again your growing method, strain, nutes, ...etc factor in too. Of course you go go conservative and do 800 and see how the plants react going that way. Regarding chlorine...see this thread. BTW, chlorine does not count against ppm readings. Try it out...test your water at tap and then after 24~48 hours...you won't notice a difference.

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Wow. 10ppm is a lot of chlorine. I guess I should have put a disclaimer in regards to a grower's local water quality. Here according to the city water quality report chlorine ppm range is 1~3 ppm...but IME I saw no significant change in ppm in a 48 hour time span when testing tap. I guess in the end it doesn't matter to me because at times of laziness or emergencies I've used straight tap water without allowing chlorine to evaporate without any negative consequences.

ppm is total ppm of everything. if your shooting for 800ppm and your tap water is 200ppm you need 600ppms of nutrients. the reason why RO or distilled water is so good is because you allow the plants to uptake more nutrient that they can use. be careful though, some companies use different ppm scales: KCl ppm is ECx500 = ppm which is the same as TDS, NaCl ppm is ECx700 = ppm, so it is best to use EC or CF readings as they are standard