Ph goes down as EC goes up?

The details - two Oasis feminised plants growing in a NFT system with a 20 litre reservoir, with about 3 weeks flowering left to go before harvest. Now, a technical question - while my plants are looking fine these days, I've noticed that the ph these past four days or so keeps sliding down to around 4 every morning, and my EC meter keeps reading 2.3 or 2.4 despite the fact that I haven't put any nutes in the res in some time. Now, I've been bringing the ph up to around 5.5-5.8 each day by simply throwing in fresh water, and the plants are looking healthy and green. Bud mass continues to develop, if not spectacularly. So, I'm simply curious as to why I'm getting these numbers, and what this bodes for the future.

all best,
jash

A drop in ph like that COULD be a sign of dying, diseased roots.....how are yours looking? I'm not saying it IS......only that it COULD be.

hey weedhound - i checked the roots and they look totally fine...also fished around the reservoir a bit and didn't drag out any diseased / dying roots...so i don't think that's the problem...what's really weird is that i was out of my house today for about 8 hours, and when i returned i compulsively checked ec and ph...and guess what?...they're markedly up and down respctively again!

Now, I don't want to get too freaked out as the plants seem perfectly healthy and they only have about twenty or so days to go at most...but is this cause for concern? maybe i'll just drain the reservoir out entirely tomorrow and start afresh.

i should add somewhat abashedly that daytime temps are very hot indeed now (close to 100F), though nights are fine...might that have anything to do with it?
best
jash

Typing from phone so this is tough

Ph up and ec down means one thing

Plants drinking more water than nutes

concentration level too high

Start with lower ec until ec goes down daily than increase ec until you find your plans balance

This is critical u will g get nutient burn Amex suck the nutes out of plant

sorry said it backward

Ec up and ph down I meant

Ec up and ph down I meant

I thought i saw that somewhere also...It's in someones sig either here or at IC

Thanks for the advice Herbie...i threw in more fresh water yesterday after you wrote, and noted this morning that the ph stayed steady at just above 5, and the EC is finally inching downwards...will try and get EC down to 2 and bump ph up to 5.5 or so and keep these numbers steady through harvest...thankfully, the plants look absolutely fine so no real worries there (for now!).
best
jash

ph and even ec are good tools because u can't chase plants

Look good and sick are references to what u did last week

I'm sure u caught it in time