Is ph drifting too low

Strain = Unsure (blues) that all I know
How many plants = 2
Veg or flower = 39 days flower
Indoor or out = indoor
Soil or hydro = hydro x2 205 gti nft trays
Res size = 20ltr each
Medium = 3" rockwool cubes
Light = 600w hps in parabolic shade
Room temp = 25.7c - 26.3c lights on 21.5c lights off
Humidity = 45% lights on 50-55% lights off
Res ph = 5.7 - 6.3 depending on drift
Pests = only kids (no pests)
Nutrients = now in flower microbial,Dutch pro take root, Dutch pro A&B bloom one tray dutchpro explode other tray bloombastic
Ec levels = now in flower between 1.6 & 1.8 high I know but very little burn
Room size 1.5m x 1.5m x 1.8m
100ltr top off water butt ph'ed water only to 5.8-6

Hi you may have read one of my other threads similar to this but now I need advise on ph that's drifting too low.

Only one of my nft trays is effected in this way.
I am in my 39th day of flower and over the last week or so the ph in this tray seems to be dropping slightly everyday.
I change the nutes in both trays every Sunday and set the ph as close to 5.8 as I can but over the last week this effected tray ph has dropped to 4.8 and I'm not sure why.
I have a 100 ltr top off tank just with microbial added to ph water set at 5.8-6.
So every day the ec drops around .1 in both trays and so by Sunday which is res change the ec value is around 1.
Roots are lovely and White,the res water is clear,no salt lines and no smell what so ever and the plant looks healthy.

So the question I am asking is....... Do I just let the plant do it's thing or shall I bring the ph back up to it's optimal range say 5.5-5.8?

Any advise would be good.

Cheers

my guess is root rot or some other form of bacteria build up in the water causing the ph drop out! ether that or your meter needs calibrating thats my best guess all i know is something isnt right.

Hey Triggertrevor, I find my PH will drift lower when my PPM's/EC is pretty high and the plants are taking more water than nutes. I find that the best thing if your going to continue running the high PPM's/EC is to stay vigilant and make sure that your adding water with a higher PH to compensate. Otherwise you could lower your PPM's and see if you can get your PH to drift normally and see if you develop deficiencies. Some strains I have found though love the high PPM's for some reason which means that I just have to watch them that much more closer. Good luck and happy growing.
KnB

kushnotbush said:

Hey Triggertrevor, I find my PH will drift lower when my PPM's/EC is pretty high and the plants are taking more water than nutes. I find that the best thing if your going to continue running the high PPM's/EC is to stay vigilant and make sure that your adding water with a higher PH to compensate. Otherwise you could lower your PPM's and see if you can get your PH to drift normally and see if you develop deficiencies. Some strains I have found though love the high PPM's for some reason which means that I just have to watch them that much more closer. Good luck and happy growing.
KnB

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Cheers for that.

Its res change on Sunday so I might lower the ec and see what happens.
Whats funny is the other plants ec strength is the same and ph is stable at around 5.5 but this plants on bloombastic not dutchpro explode.
I'll just keep my eye on it as there's no tell tell signs of any problems as yet.

Cheers

drgreentm said:

my guess is root rot or some other form of bacteria build up in the water causing the ph drop out! ether that or your meter needs calibrating thats my best guess all i know is something isnt right.

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My ph pens fine as it's reading my other nft tray and my 100ltrs res fine and I also calibrated it 2 weeks ago.

If it is a bacteria issue what would be the signs.? As there's no signs of off colour roots or any smell and like I said the waters crystal clear with no salt lines on the side of ge res?

Cheers

Triggertrevor said:

My ph pens fine as it's reading my other nft tray and my 100ltrs res fine and I also calibrated it 2 weeks ago.

If it is a bacteria issue what would be the signs.? As there's no signs of off colour roots or any smell and like I said the waters crystal clear with no salt lines on the side of ge res?

Cheers

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Then it's not bacterial. If your plants look good, everything is fine.

Triggertrevor said:

My ph pens fine as it's reading my other nft tray and my 100ltrs res fine and I also calibrated it 2 weeks ago.

If it is a bacteria issue what would be the signs.? As there's no signs of off colour roots or any smell and like I said the waters crystal clear with no salt lines on the side of ge res?

Cheers

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well sounds like the plants look healthy and happy, if the roots are not discolored or slimey/smelly i wouldnt worry just stay on top of the ph and it should be fine. can i ask how many times you have ran this system before?

drgreentm said:

well sounds like the plants look healthy and happy, if the roots are not discolored or slimey/smelly i wouldnt worry just stay on top of the ph and it should be fine. can i ask how many times you have ran this system before?

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This Is my first time in hydro/nft previous times have been in soil.
I think once everything's setup correctly and dialled in it a good system and at least it gives you more of a warning than soil when things go wrong.

Cheers

*****UPDATE TO ALL WHO HAVE KINDLY OFFERED THERE PEARLS OF WISDOM******

This morning I drained 10ltrs from the ph effected nft tray and replaced it with 10ltrs of ph5.9 water from my top off tank and tested the ph of that solution onced mixed by the pump and my findings were exactly the same.
The ph was back to what it was when I started ph4.8 with a lower ec of 1.2.

So I'm slightly confused with this one.

Cheers