Switch to bloom nutes?

[Handyandy]

Yes I try to get at least 15-20% run-off every feed (twice a day currently). My last few feeds have been closer to 600 than 800 and yes includes my water ppm + PH up.
I think you're right about the possible salt build up/nute lock-out. Last week, my run-off PPM was measuring 400-500 higher and this week 300-400 higher. Been considering a good flush but plant hasn't shown any real issues till now.
Here are updated photos (day 40).

 

[Handyandy]

Update: Last feed run-off ppm only 200 higher.
Last week or so I reduced the feed ppm and been watering with more run off to try gradually flush the coco and it seems to be working.
Run off PH measures 6.8-7.0 but I don't think this is the true PH of the medium from what I've read.

 

[Waira]

... you're the second person in here with pH going up in run-off in coco, very very weird,.... pH going in is about 6.0 you say? How much of the ppm is the water's base?
You mention pH up- ? not sure why, is the nute solution that low that it needs it?

 

[Handyandy]

Yes PH going in around 6 but always comes out in high 6’s. My tap water ppm measures 50-60 and around 7 PH. Depending on the ppm and mix of nutes I add, the ph drops to mid 5’s and I add a drop or 2 of PH up to bring up to 6.
One thing I suspect is the PH up. I use an organic one and I suspect the PH keeps rising as time goes on. I have been monitoring the run off PH regularly but haven’t taken any actions as the plant has been relatively happy so far...

 

[ion]

I wonder if pH-up is building up in the medium even though you are getting runoff when watering? I'm not an experienced grower but once I made up a nutrient mix in a bucket, all balanced with pH @ 6.0 and something came up and I forgot to water until the next day. Before I watered I tested the pH and it had risen in the bucket overnight. It went from 6.0 to 6.4 sitting in a bucket. I'm wondering if that's happening in your medium? Now I use nutrients to adjust pH levels.

 

[Handyandy]

I think you’re on the money. I suspect that’s exactly what’s happening. Because I use PH up almost every watering/feed, the coco always contains PH up and it rises over time.
I’m not sure if I can avoid using PH up as I’m following a feed chart and would need to alter ratios to achieve a certain PH??

 

[Waira]

:smoking: good on the water ppm's, that's fine,.... in fact, low CaCO3 water is going to show bigger pH changes from small inputs because of the lack of buffering minerals in there,.. RO/Di water is this in the extreme, they can swing wildly from even small inputs,....like CO2 dissolving back into the water (forms carbonic acid) will bring ph down, keep in mind how little CO2 there is in the air = 0.04% ..... are you using any Ca-Mg supp's? You should be in coco, especially with that water, unless the nutes are coco specific (which I highly recommend),....add that first to the water always,... then your nutes.
"organic" pH up, what exactly does the label say it is, a carbonate sourced ingredient?

 

[Handyandy]

The organic PH up is made by a reputable local brand but strangely does not list ingredients! The line of nutes I’m using are derived from natural sources (chemical free) and that’s why I wanted to use natural/organic PH up/down to go along with it. The nutes are recommended for reservoirs and coco with specific feed charts, which is what I have been following with reduced strength. It has a CaMg supplement but I have phased it out now (bloom stage) as per feed chart.
I left the plant outside yesterday as it was a nice sunny day but when I got back home, the coco was very dry. Now the run off ppm is +400 (before +200) and PH measured 7.40 (6.1 going in). I’m starting to get alarmed, even though the plant doesn’t seem to be showing any negative signs (yet). Thinking about mixing low strength nutes to make solution PH 5.8-6.2 without the need for PH and flushing the coco. Any suggestions or advise??
Thanks for everyone’s input on this