Can’t get pH down in coco

Hello all. I’m new to growing and have ran into a similar issue on both of my first runs so far. So during veg everything looks good and plants are healthy. In flower, right around week 3 or 4 I start noticing that the top leaves start to turn yellow and growth slows. On this run I tested the runoff and my PPMs were ok but my pH was close to 7. So the last three feedings I fed at a ph of 5.5, but the runoff ph didn’t go down and plants are getting worse. So I finally researched my nutrients and it appears that the AN Big Bud I’m giving is the coco one. After reading up on it, it looks like it already has calmag and iron added. Meanwhile I have been giving 3ml/g of calmag with all feedings and watering. Even when I flushed I used calmag and RO water ph’d to 5.5. So my question is do you think this has caused an excess of calmag and locked out trace elements like iron, which is causing the yellowing? My plan was to flush with a flushing agent like FloraKleen ph’d at 5.5 and then just give a light feeding of base A and B. Do you guys think that’s a good plan? I’m in week 5 and this is already looking like it’s going to hurt my yield.

Stop checking the run off ph

Feed with proper PH’d feed and forget about the rest.

Look on your bottles of base nutrients, does it say anywhere on it "ph perfect"? If it does, you're not supposed to be using ph up or down with it.

Ignore the ph of the run off its irrelevant, ph your nutrients appropriately and feed the plants with it... Job done!
Your adjusting it from right to wrong by altering the ph to so low.

Star Dog said:

Ignore the ph of the run off its irrelevant, ph your nutrients appropriately and feed the plants with it... Job done!
Your adjusting it from right to wrong by altering the ph to so low.

Click to expand...

I was just feeding at 5.8 to 6.0 the whole time. But like I said, they started yellowing on the top leaves right around week 3 to 4, which is when Big Bud starts. That’s why I checked the runoff, I thought maybe it was nutrient buildup. But the PPM is only around 1400 and I feed at about 1500. But like I said, I noticed the ph almost at 7. I’m trying to figure out why the yellowing and to stop it and hopefully turn it around. I had the same issue last run but I never checked the runoff and eventually the buds stopped growing and yield suffered.

Mookjong said:

Look on your bottles of base nutrients, does it say anywhere on it "ph perfect"? If it does, you're not supposed to be using ph up or down with it.

Click to expand...

Nothing is ph perfect. The only thing is the Big Bud says coco. Everything else is regular.

Do you have pics of said plants?

bk78 said:

Do you have pics of said plants?

Click to expand...

I will get some later this afternoon and post

1500ppm? That’s absolutely bonkers

In full blown flower I never go over 800 and my tap water sits at 150

biz642 said:

I was just feeding at 5.8 to 6.0 the whole time. But the PPM is only around 1400 and I feed at about 1500. But like I said, I noticed the ph almost at 7.

Click to expand...

Isn't that a lot of ppm unless your room is dialed? Which it may be, idk.

I feed at 5.8 -6ish. it comes out ROUND 6-6.1.

I had a terrible time with ro and nutes, I was using cal/mag to buffer. I'm not adding extra cal/mag at all now, I just feed what is in the dyna gro bottle.
Now, I take my ro water. 12ppm,7ph
ph to 5.5ish and use 1.5ml/gal armor Si, that raises the ph to maybe 6.
Add nutes
usually end up 5.8-6, I adjust when I feed if needed.
Make sure you water to run off, it flushes old nutes and feeds new nutes and oxygen each time you feed. 20%, sp 1000ml feed = waste 200ml.

My solution climbs in ph sitting there. it will be 6.3 in a few days after I mixed it at 5.8ish. It climbs when plants eat to, they put out chemicals that change the ph of the root zone when they eat.

Agree with BK, most likely your issues are due to the high ppms. If you're feeding at 5.8, you're good. A runoff of 7 is not an issue. I don't ever go above 700 ppms, and I'm thinking 600 might even be better for me.

If his meter is on the 500 scale........that puts his EC at 3.0.
Wow!!!!!

It’s at 700 scale. Been feeding 1200-1400 during veg. A buddy of mine feeds at 1900 to 2000 with no burn lol. So you guys think it’s nutrient burn and not the calmag issue with Big Bud coco and additional calmag?

I'm having a really hard time seeing the pics, might be tiny little aliens with flamethrowers. idk.
I'm new to growing like you are. It takes time and experience to learn to read plants. Only on way to get that.

Here, these, and that link above have tons of info.
https://dutch-passion.com/en/blog/a-visual-guide-to-cannabis-deficiencies-n987

bk78 said:

1500ppm? That’s absolutely bonkers

In full blown flower I never go over 800 and my tap water sits at 150

Click to expand...

I run 900 max and my tap sits around 250. My experience is similar.
PS you can't overwater coco unless you don't have roots

Also, I didn't know about buffering coco before. I did rinse it good and let it sit in nutes before though.
Next time I'm doing this. 1 g/L solution of calcium nitrate and then with 2g/L of tetrasodium EDTA .
Same thing as above, just has instructions on how to buffer.

biz642 said:

I was just feeding at 5.8 to 6.0 the whole time. But like I said, they started yellowing on the top leaves right around week 3 to 4, which is when Big Bud starts. That’s why I checked the runoff, I thought maybe it was nutrient buildup. But the PPM is only around 1400 and I feed at about 1500. But like I said, I noticed the ph almost at 7. I’m trying to figure out why the yellowing and to stop it and hopefully turn it around. I had the same issue last run but I never checked the runoff and eventually the buds stopped growing and yield suffered.

Click to expand...

Isn't EC a universal scale everyone understands without guessing scales?

Anyways i've just checked my truncheon and I'm certain that's where your problem is 14/1500ppm is brutality strong, my EC at the highest during flower is only 1.1/1.2 ec

curious2garden said:

PS you can't overwater coco unless you don't have roots

Click to expand...

Neat. Yeah grow weed easy states that on their website