Forget about ppm or ec for a while,ph is way more important,we will get to it but not just yet.
As long as the ppm or ec ratio is mixed correctly by following the manufacturers mix chart you can do the whole grow without ever knowing the exact ppm or ec & have excellent results,ph levels are not like that,its one of the most important issues.
Ok now lets ph your freshly mixed nutrient water,your ph allways changes after any nutrients are mixed this is why we allways adjust the ph after all nutrients are added to the water,trying to control ph levels with higher or lower levels of nutrients instead of using ph up or ph down is possible but should be left for serious expert growers,we use standard ph up or down.
Now you measure the water nutrient mixture & see that the ph is out of accepted range which we know is from 5.5 to 6.5,if the ph is to high you add small amounts of ph down & stir the water,then re measure,repeat the process until your reading 5.5 or within a few points lower than 5.5,going down to a 5.2 or 5.3 isnt going to hurt anything,now that you have the proper mixture of nutrients by following the chart & have adjusted the ph to the low end lets talk some more about ph before we go further.
The reason you adjust the ph to 5.5 which is the lowest your supposed to go is that the ph levels never stay in one place,they constantly float around & in most of the growth stages the ph levels will rise up daily from the 5.5 level you adjusted it to,the very next day the ph will be higher,this is ok & perfectly normal.
Every day the ph will fluctuate,when you read the ph of the water the daily reading will determine how you proceed,example,if you adjusted the ph at 5.5 on day one & when you measure ph on day two it reads 5.9 you dont need to do anything,as long as the ph stays under or close to 6.5 there is no need to adjust the ph.
Remember when i said different strains prefer different ph,this is where that comes in,the more you get used to controling the ph levels by keeping the ph range between 5.5 to 6.5 from adding ph up or ph down the more comfortable you will get in correcting the ph,this is when you will start to notice a pattern in how fast the ph climbs away from the starting point of 5.5,you'll notice where the ph holds steady for a day or two,or you'll notice a decrease in how fast the ph climbs or decreases,this spot on your meter will be around 5.8 but not allways,the sweet spot can be anywhere within the 5.5 to 6.5 range we know is your working ph range,until you get skilled enough to see the sweet spot the plants prefer to be at play it safe & hold the ph at 5.8,you dont have to constantly be at 5.8 but when the ph is close to going out of the 5.5 to 6.5 range thats when you adjust to the sweet spot of 5.8,the plants prefered ph range might not be right at 5.8 but until your skilled enough to see exactly where the plant prefers the ph to be its safest to stick with 5.8 until you learn more.
Also,for short periods of time most strains enjoy going outside the 5.5 to 6.5 range,it will not hurt the plant if the ph drops down to a 4.9 for a short time,the same goes for the other extreme of ph range,it will not harm the plant for the ph to go up to 7.1 for a very short period,infact plants that are allowed to see these lower & higher ph levels will show better overall health,remember where i said different nutrients have different absorbtion rates at lower or higher ph levels,this is where allowing your ph to float comes into play by allowing the plant to see higher or lower ph ranges where the plant can best make use of the nutrients available for it to consume.
Keep in mind that allowing the ph to float past the accepted safe range of 5.5 to 6.5 should only be done for short periods of one day,anything longer can damage the plant,if the ph is out of range & dont move back into range within 24 hours then you adjust it back into the 5.5 to 6.5 range,when adjusting ph try not to adjust in large increments,example,if the ph is up to 7.1 you dont want to adjust it back down to 5.5 all at once,spread out large adjustments to the ph over the couse of a day.
Once you become more skilled & your comfort level grows you'll know more about the strain your growing,until those skill & comfort levels are reached be sure to make all adjustments in increments of no more than 1 ph point at a time,drastic all at once ph adjustments can shock some plants.
This is all i have time for at the present,got to take the wife to the doctor in a few hours so i got to help her get ready,i will continue your lesson later today.
If any member see's something ive missed on the ph feel free to correct my posts so we can better help this new hydro grower.
It would be nice if some more skilled hydroponic growers could chime in with some detailed information so maybe together we can make this thread a step by step introduction to hydroponics for newbs.
More to come this evening.