ph keeps climbing

does using pea gravel in my E&F table raise the ph?My current setup is pea gravel for medium,AN connoisseur,big bud ,carbo load,sensizyme,b-52 in RO water.When i change the water i dont even bother adjusting the nutrients ph upward (as it is usually about 4.8 at the finish of change) cause after a couple of flood cycles the ph is around the 5.6 range advanced nutrients recomends.My ph gets as high as 6.4 after 1 lights on event from 5.6.I check it 2 times a day,and i have to adjust down both times.I adjust back to around 5.6 and repeat.
I keep my nutrients moving all the time with air bubbles as well as a second water pump turned on its side to circulate water around tank.
My plants are starting to show signs of calcium and magnesium defficiencey,i was reading a site from a commercial hydro grower and they suggested keeping a ph range between 5.1 - 5.4 for optimum calcium uptake.Does anybody have any feelings/oppinions about this.they suggest most nutrient companys do not have all the facts on ph ranges.A lot of companys suggest 5.8 as a base ph,AN recomends 5.6.
AN says there is a suitible amount of calcium and magnesium in there bloom formula and there calculator does not show using any kind of calcium or mag. supplements for the whole bloom cycle.i question this especially using ro water,however if the ph is not in the optimal range for ph uptake which is below 5.5 or above 6.0 the 5.8 base ph is right in the middle where uptake is diminished,so even at 5.6 the uptake is not as available as it would be at 5.1.even if there is some in it the plant isnt absorbing it
I am going to try adjusting ph to 5.1 and let it drift upwards of 5.9 and bring it back down again instead of adding cal mag at which the plant isnt absorbing anyway at the 5.6-6.0 range anyway
just really wanted some other input/experiences on ph issues similar to mine

The pea gravel? Is it hydroponics? If not its probly not inert, like L.E.C.A, light expanded clay agragate. Could be your water. You just RO it no DI.

from what ive read pea gravel is inert unless its limestone gravel which i am positive my gravel is pea not limestone.Ive always used pea gravel but i always used coco coir mixed in to help keep moisture content up.i did away with the coco because it would fall apart.My ph used to rise,but it would take a few days to get up above 6.5 from 5.8.I was just curious to find out if cutting out the coc from the pea gravel is my variable that changed or if it is something else.
I did 1 light cycle with ph at 5.1 and let it drift last night.i checked ph this morning and it was at 5.5 so i left it alone.checked it after work and it was 5.9 so i adjusted it back to 5.1.I checked on the plants and they actually looked perkier than they have been looking.ie leaves are standing at 45 degree angle,leaves got some color back in the leaves that were starting to show calcium defficiency.Im going to keep the ph in the 5-6 range and i will see what happens.so far so good

Wow that's fast. You should to an experiment. Mix just a little bit of your nutrients up. Just enough to test the Ph, and see what that does. Google DI-ionization, it strips the ion from the water molecules. You find out its the ion that makes your Ph rebound like that. Should look into a RO/DI system.

I will try mixing up brand new nutes to test.ill mix up two small batches one with pea gravel one without and test ph after a day or two.I will look into di-ionization,that was a route i had not considered or knew of for that matter.Thank you for the info