Ph problems! Did my research but no solution found!

Strain: CC 818 Headband
Stage: 9th Day of Flower
Media: Bottom third Hydroton/Middle Rockwool cubes/ Top Hydroton
Method: Hydro (2 5gal Flood and Drain buckets) Oxygen Pot System /with 55 gal Res
Nutrient: Blue Planet Nutrients 3 Part (synthetic)with Seaweed and Root Magic + Cal-Mag
Water: 20% Tap water at 70 ppm/Ph 6.4 80% RO water at 10ppm/PH 5.4
Lighting: Two BD XLs (750w ea) LED
Training: Each plant has its own Scrog Net
Temps: 84F Leaf surface Temps Lights on/ 65-73 Lights off
Humidity: 50-65
PPM: 640


Im having a hard time trying to figure out why my ph is dropping. I ph up my res to 6.1 and in 24hrs it gets as low as 5.4! My roots are very white and my plants show no signs of def. Matter of fact I brew a tea every week. The base of my plants are at least 2in in diameter! I veg these girls for 8 weeks. They look very healthy and are reaching for the lights. I spotted my first pistols about 5 days ago! Im concerned because I leave in about three weeks and I want my ph to be a little more stable then that. I have someone to adjust the ph while Im gone but thats about it. Im leaving for two weeks and my plan is to do a res change before I leave.


I have a Tri-meter by nutradrip that sits in my res 24/7. I calibrated it today with 7.0 and 4.01 solution. My 7.0 solution reading was 7.1 on my meter and my 4.01 reading was spot on before I made that .1 adjustment. The nutrient solution temp stays at 65/66 with the help of a chiller.

ANY HELP OR INSIGHT IS HIGHLY APPRECIATED!

Pics?

Im trying to upload now!

They are from seed. Two diff pheno. Note: These were taken Day 2 of flower. They have grown alot since the pic but they still look really healthy in my opinion.I have my space dialed in. Ive done my homework! I just have never had to add ph up in any other grow.

This is the more sativa dom pheno. This is the more Indica

I just want to know if anyone else has ever had this problem! And if so how did they fix it? Or is it just strain specific?

Root rot will create bacteria and that will drop ph. Did you wash your hydroton before using? Unwashed hydroton can change your ph. nutrients can change the ph. I noticed you didnt take pics of the roots that would be my first suspect.

As you can see I use a scrog but I did get a friend to help me check and the roots are really white! Ive rule root rot out!

Oh yeah I washed the hydroton. I soaked it in 30% peroxide and I rinsed it for over an hour. There was absolutely no dust that I saw left behind. The problem has just started during the transition phase. As you can see there are no indicators of root rot. I learned how to win that battle a while ago. When I first started root rot almost made me quit! LOL Every since I implemented beneficial teas into my feed schedule Ive had really healthy root systems.

Its your rock wool probably, if it had a heavy amount of lime in the rocks spun out it can cause your ph to swing. I had a friend that always complained about his rock wool having odd ph fluctuations.

Yeah when I first started using rockwool I had big problem because I didnt soak it correctly. But the problem was really high ph. Who knows you might be right but if thats the case Im screwed. I did my rockwool until I got a run off of ph 5.6. This has worked for me for a couple grows now. Every grow is different for me so who knows. Ill just keep a eye on things and hope for best. Searching for that gram per watt. Im getting close.

Seems a little fast to do within 24 hours, but the pH will change as the nutrients are used from the reservoir. Evaporation with also effect it. I've never use those nutrients, so it could be that, or maybe how you mix has something to do with it. Do you top off or complete change?

Could be something as simple as a dead pH meter. They do die.

The acceptable PH range for a flood and drain table is 5.5-6.2. I swap the res out every seven to four days depending on the growth and top up the res with fresh water every 24 hours. I can tell by the appearance that there isn't any root rot.

I am a cheap skate and lazy so I use very sparing amounts of rockwool. I've even figured how to use the soft stuff you get in a bail for insulation. Less rockwool...more rock.

bird mcbride said:

The acceptable PH range for a flood and drain table is 5.5-6.2. I swap the res out every seven to four days depending on the growth and top up the res with fresh water every 24 hours. I can tell by the appearance that there isn't any root rot.

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Unless aquaponic ... I shoot for 6.8

6.8 is acceptable for a soil.

The higher the pH, the harder it is for cannabis to use the nutrients in the water, as far as hydro. I use 6.8 because it is aquaponics and I care about my fish.

Could too much beneficial tea cause the problem. That the only other thing I can think of.

As you add more nutrients (in most cases), the pH will go down.

I always do complete res changes. I never top up other then using plain water to dilute the water in between res changes.