THROUGH THE VEGETIVE AND FLOWERING STAGES YOUR MARIJUANA PLANTS ARE GOING TO NEED EXTRA P.H.(PHOSPHOUS) DAILY. THE INTAKE VARIES AS TO THE NUMBER OF PLANTS YOU ARE GROWING, THERE PRESENT SIZE, THE STAGE THEY ARE IN AND, SIZE OF YOUR RESOVOIR ECT. SO, TO KEEP A ACCURATE MEASURMENT OF THE P.H. IN YOUR RESOVOIR WE USE, P.H. TESTING EQUIPMENT. THERE IS A COMMON SCALE USED TO MEASURE THE BALANCE OF YOUR P.H. CONTENT. WEATHER IT BE IN HYDROPONICS, SOIL, OF EVEN THE DAILY P.H TESTING THAT IS REQUIRED FOR A SWIMMING POOL.  THE SCALE IS SET OUT FROM NUMBERS 1 TO NUMBER 14.  THE NUMBER SEVEN OF THIS SCALE IS CONSIDERED THE P.H. MEDIUM.  THE LOWER THE NUMBER ON THE SCALE THE MORE ACIDY OR ACIDIC THE CONTENT IS OF THE SOLUTION, OR SOIL.  THE HIGHER THE NUMBER IS, THE MORE ALKALINE OR ALKALIDE THE SOLUTION IS, OR SOIL. P. H. TESTERS CAN BE ELABORET OR QUITE SIMPLE.  I PREFER THE SIMPLE IODINE, ALCOHOL BASED, TESTERS WITH THE USE OF A EYE DROPPER.  ALSO THESE ONES COME AS DIPPY STICKS.  THEY ARE DIPPED INTO YOUR RESOVOIR SOLUTION AND COMPARED TO A CHART OF COLOURS ON THE SIDE OF THE BOTTLE, OR THE SIDE OF THE BOX. THE CORRESPONDING NUMBERS WILL HAVE A MATCHING COLOUR ON A COLOUR CODED CHART. FROM WHAT I HAVE READ OVER THE YEARS AND EXPERIENCED FIRST HAND MYSELF, I HAVE FOUND MARIJUANA TO THRIVE BEST WITH A P.H BALANCE OF 5.5 TO 6.0 IN THE VEGETIVE STAGE, AND A P.H. BALANCE OF 5.3 TO 5.7 IN THE FLOWERING STAGE. IN THE BEGINNING OF A CROP AND TO THE END I MONITOR THE P.H. DAILY.  IN THE FIRST STAGES I ONLY NEED ADD SMALL AMOUNTS AND SOMETIMES NONE AT ALL.  AS THE PLANTS GROW QUITE LARGER THEY REQUIRE MORE P.H. AND THUSLY START TO USE MORE OF IT UP.  DAILY MONERITING OF P.H. EVENTUALLY UNFOLDS THIS FOR YOU TO SEE FOR YOURSELF FIRST HAND. PHOSPHORIC ACID IS A REQUIRMENT NEEDED IN GROWING BIG HEALTHY PLANTS, THAT EVENTUALLY WILL YEILD YOU, BIG HEALTHY BUDDS. THE HYDRO STORES AROUND HERE CARRY TWO TYPES OF PHOSPHORIC ACID A 80% AND A 20%, IM SURE THERE ARE OTHERS TOO.  I SUGGEST YOU USE THE 20% TO START WITH, UNTIL YOU LEARN ABOUT YOUR MARIJUANA'S P.H. THE 80% IS VERY STRONG AND TOO MUCH CAN BE ADDED EASILY.

NOTICABLY, YOUR PLANTS WILL SUCK UP YOUR RESOVOIRS SOLUTION DAILY, SO YOU ALSO NEED TO DO A DAILY TOPPING OFF OF MORE WATER.  CHECK THE P.H. OF JUST YOUR WATER WHERE YOU ARE AND LIVE.  HERE IT IS ABOUT 6.8 TO 7.3 IN THE ADDING OF WATER DAILY YOU WILL SEE THAT THE WATER WILL RAISE UP YOUR P.H CONTENT.  IF YOU ADD MORE OF YOUR CHEMICALS THIS WILL DO THE REVERSE AND LOWER YOUR P.H. TOP YOUR RESOVOIR FIRST, THEN ADD YOUR NUTRIENTS, THEN DO YOUR P.H CHECK.  IF YOUR BALANCED OUT PROPERLY ADD NONE, IF YOUR RUNNING A LITTLE HIGH LOWER YOUR P. H SCALE WITH THE USE OF SOME OF YOUR PHOSPHORIC ACID.  USE ONLY A VERY LITTLE HALF A CAP MAYBE EVEN LESS, MIX IT REAL GOOD AND TEST AGAIN, THIS WILL HELP TO ENSURE YOU DONT ADD TO MUCH, IF YOU NEED A LITTLE MORE, ADD AGAIN, AND RETEST AGAIN. TO MUCH P.H. AND OR TOO LITTLE P.H. IS A PROBLEM EITHER WAY, THATS WHY THIS IS SO IMPORTANT.  THE PLANTS WILL NOT BE ABLE TO USE THE NUTRIENTS IN YOUR SOLUTION FULLY WITH OUT THE PRPOER BALANCE OF P.H. YOU SHOULD NEVER NEED A "P.H UP" YOU SHOULD ONLY EVER NEED TO USE THE PHOSPHORIC ACID AS A "P.H. DOWN".  THIS IS BECAUSE AT ALL STAGES IN YOUR PLANTS, AND IF THEIR GROWING HEALTHY, WILL USE IT UP, THEREFORE ALWYAS RAISING THE NUMBERS ON YOUR P.H. SCALE. OTHER EXPENSIZE ELECTRONIC TESTERS AND EQUIPMENT IN MY OPINION ARE A WASTE OF MONEY, AND CAN BE AT TIMES INACCURATE.  THEY REQUIRE THE EXTRA PUCHASE OF A MEDIUM P.H. BUFFER USED TO CALLOBRATE THESE TESTERS.  THUS YOU SPEND NEEDLESS TIME AND MONEY FOR SUCH A TESTER TOOL.