Questions about runoff pH/EC in Coco/Perlite

Hey all,

New here and thought I'd make my first post a question about a current grow. Plants look healthy, but maybe my worry isn't unwarranted?!

Grow details:
Not my first grow, but my first grow in about 3
5x5x6'6" Tent
1000w HPS light
5 plants, vegged 90 days
4x GG#4 Canuk seeds
1x Blueberry Fem, also Canuk seeds
All are in 10gallon fabric pots with ~50/50 coco/perlite
Feeding GH Micro/bloom with protekt and some calmag (discontinued protekt and calmag last week after flowering stretch mostly complete.)
Feed is being pH'd to 5.6-6.2.
Feed was running ~1100EC max
Admittedly was not running much runoff, which is where my worry comes from currently I believe (more on that soon)
Temps with lights off 17-21C, usual temp at lights off ~26C. Running 12/12 from 7:30pm to 7:30am.
RH for the past weeks has been 45-58
Now on day 29F


Plants look extremely happy, have plenty of budsites, and are packing on flowers daily. Almost outgrew my tent both in height and width (wish I only had the 4 plants). Overall though, these plants are very impressive to me as this is my first grow in YEARS and they're my largest plants ever. My current worry though, arose the other day as I decided to measure the runoff pH from my plants. Feed went in at 6pH and 1100EC. Gave it about 6L of feed that day. Much to my surprise the pH of the runoff measured 4.2 and EC close to 3000! Figured it would maybe be that one plant, so I went ahead and measured some others. Got readings anywhere from 4.2 to 4.6 pH on the runoff, with EC of 2400-3000. Decided that was a pretty extreme difference from inbound feed, so I decided to take action.

So I went ahead and cleaned the trays because they have salt buildup. Next feeding I fed nutes diluted to 1/2 strength with tap water, bringing EC to ~700 and pH to 6.4. Runoff read the exact same as prior. So today I decided to give each plant 6-8L of tap water pH'd to 6.5 (300EC). That gave me about 3L of runoff since they were still fairly moist from prior feed, and that runoff still measured 4.5ph and 2200-3000EC! No signs of nute burn or lockout or stress at all yet but I'm worrying it could happen quick if nothing is adjusted.

So my question to you all, is what would you do in this scenario? Would you continue on as if you haven't noticed, as the plants look happy? Should I continue feeding low strength and slightly higher pH until I see runoff come out closer to inbound?

Some pics below.

Be more aggressive when flushing. Just straight water and thoroughly produce some runoff.

Do you think it's necessary, or could I continue on since nothing negative has cropped up yet?

Let them dry down and water again straight water. Check the runoff when you do. See what it says. Likely get a flush of white hairs when it drops back down. Id look at flushing periodically using passive hydro type setups.

Regardless of what was posted above.......never, ever give plain water and never, ever let it get dry when in coco. If you want to flush the coco, use a weak nute solution.
You should be feeding at least twice per day to substantial run off.......and don't let it sit in the run off.

Good luck.

Coco college...

Thanks for the advice. I have heard the NEVER USE PLAIN WATER IN COCO a million times before, but have yet to have anyone explain why? Not saying it's something I normally do, but would there not be a certain amount of residual nutes in a medium that could be rehydrated with plain water if pH is adjusted? At what point does it become "weak nute solution" of an acceptable weakness for my flushing purpose currently? 1/2 strength? 1/4 strength? The reason I question that is because my tap water alone is 1/4 of the EC content of my usual feed @ 280-300EC...

And at what point would you all deem the runoff levels acceptable to resume as normal? It's hard to judge since the plants aren't showing any signs of stress/deficiency so there aren't really many visual cues for me to follow, only runoff readings.

I grow in coco loco and found 1 liter of run off per gallon of water per plant. I stopped getting run off with each gallon though. It took two gallons of buffered cal mag water to flush the roots. A salt is chemistry talk for anything with 2 or more ions, organic and synthetic both have them. A nitrogen ion is a nitrogen ion. No matter if its organic or not. I personally feel getting a healthy run off, one liter per gallon, is very important. Calmag will account for about 35% of your total ppm or ec

Pulled them all out yesterday which was a collosal pain in my ass (and back). Put them in a large under bed storage container and have them about 15L of weak feed ph'd to 6.2ish. Got a ton of runoff, and a good workout hauling around saturated 10gallon pots in the tight space I had to work in. Hopefully that's the last time I've got to pull these out prior to harvest.

They really are beautiful, and I managed to get into the back of the tent finally to take a better look at my blueberry plant. It seems that it's starting to turn purple too. Calyx colours are changed at the tops!

Since so many people liked the first posts, I feel like I owed everyone an update. Was working on my plants just now and had a good picture session. I was originally expecting this one to go 10 weeks. I'm thinking I'll be able to harvest the top 3/4 of the buds next friday (1.5 weeks) -- will be putting the undergrowth back in until the slowest plant is done. Even if it goes into the trim pile for hash/edibles, I figure it's worth it.

Posting a link to imgur since it's 100x quicker this way through my phone, but of course it's not as nice as embedded into the thread.

Updated pics of the blueberry plant!

Final dimensions of the plant -- 24"x40" width (widest points across) 28" height from coco. This plant only stretched about 6" unlike the GG which more than doubled.

Let me know your thoughts, I'll post some pics of the GG plants shortly for everyone to enjoy as well. I'm definitely enjoying the sight every time I open my tent door!

GG#4 PICS