salt buildup + badly in need of nitrogen = what do i do?

[tweezy]

hey guys

so i've been on the DWC train for about the last 18 months but recently switched back to soil

right now i'm running 5x white rhino (in 5gals) vegging under a 1k - they're topped and about 18" tall, bushy, and dense ... great looking plants

i'm using only grow big and ph'd water for veg, alternating feedings with waterings, ph always at 6.6-6.7. since the time they were clones i've slowly bumped up the PPM so i know exactly where i'm -supposed- to be as far as this feeding schedule is concerned. (last feeding was at 850ppm and it finally caused just the tiniest of burnt edges so i know i'm walking that thin line of enough / too much)

here's the problem - i haven't been watering to the point of runoff and i think i'm encountering a salt buildup. the new growth is paler and weaker than the old stuff and on a couple of the ladies it is significantly yellow... exactly how it looks in DWC when they're badly in need of an increase in PPM. but like i said, these same plants that are in need of nitrogen appear to have very slightly burnt tips on the newest of growth.... so i can't imagine there isn't enough nitrogen in the soil right now. hence, the salt buildup diagnosis.

so i have a few questions:

1) my tap water ph is 6.5 with a ppm of about 230. could this slightly acidic water be encouraging the salt buildup? should i switch to distilled for awhile?

2) IF there truly is a salt buildup.... does all that excess nitrogen remain available to the plant if i just go forward with a few plain water-ings? or do i just need to go forward with a full flush and get all of it out there? (i'm hesitant to run 10-15 gallons of water through these plants and do a true flush, especially if my tap water might be contributing to this buildup. i have done flushes in the past and they just always seem to strip the soil of all the good stuff as well as the bad.)

3) i'm just about to get ready to flower.... would it be best to wait until this issue is cleared up? would switching to 12/12 kick the plants into the early-flower stretch and actually force them to -use- the excess nitrogen in the soil???

their growth doesn't seem to be inhibited right now, they're still gaining size daily, it's just not as spectacular as it was the first month of their life.

thanks you guys, any help would really be appreciated and i hope i've given all the information you need to help me out.

 

[praisehim.]

three things.
1) nitrogen deificiency will show throughout the "body" of the plant.
2) salt bulidup usually causes spotting or just shitty looking plants, not so much yellow like your described.
3) you need magnesium go get a bottle of cal-mag, an start at 8mls per gallon, taper it off as you see the yellowing slow down.

 

[stonedar]

I've never used just Grow Big by itself, I've always added Big Bloom. So I dunno if that has whatever Grow Big lacks or what but I've had good luck with fox farm.

 

[PoopyTeaBags]

pictures are worth a thousand words... how do you get salt build up in rdwc???

 

[ganzas]

salt buildup= maybe correct the ph level i think
badly in need of nitrogen= when the plants dont have the correct ph level, they dont can absorve the nutrients of the soil...

some pictures is the best...

Just my opinion friend

 

[PoopyTeaBags]

o i just read you feed at 6.7 - 6.8 thats your problem.... this is hydro you need to be feeding at 5.8 your a full point to high... lower your ph to 5.8 and make sure your ec meter is in the correct range... youll be green in a week... this aint soil so dont treat it as such.

and again you confuse me... you feed? in dwc? you mean that you add water back with food in it??? im confused man.

 

[tweezy]

no no i'm in soil, i was just saying i normally run with DWC but i decided to switch back to soil for this run

i'll get some pics in a few minutes, thanks guys

 

[PoopyTeaBags]

you got a ph pen? how do you get your ph??? when was the last time it was calibrated and how old is it?

 

[tweezy]

i have a eutech pen, it sits in a cap full of 7.0 calibration liquid and i calibrate it damn near every few days

still haven't had a chance to take pics yet but i promise they're coming

 

[tweezy]

you got a ph pen? how do you get your ph??? when was the last time it was calibrated and how old is it?

wow this completely reminded me of something. something i should have mentioned in the beginning.

about 2.5 weeks ago, maybe three or four waterings in a row were ph'd incorrectly. my meter was getting a little gunk on it PLUS i was out of calibration liquid so i cleaned it up with an old toothbrush and re-calibrated it with a new jar of 7.0 stuff.

since then there has been probably 5 waterings with proper PH but i know for a fact that the couple weeks of incorrect water had a negative effect on it.

my tap water comes out at 6.7 but i remember during those water/feedings my meter was reading 7.2 for the tap water (so when i lowered it to 6.6 it was -actually- 6.1)...... for some reason it took me a week or more to realize that was completely wrong and that's when i cleaned/recalibrated.

could i just have lowered the soil PH a few points and this is the result of that?

praisehim mentioned this being a magnesium problem, which i think i agree with. but i wonder if the underlying problem is that the 10-12 days of low-PH is responsible for magnesium lockout and NOT a potential salt buildup like i originally thought.

and if that's the case, i'm just not sure if i should add more magnesium if it's currently locked out or just move forward with a few non-feeding waterings until the soil PH is back in the right zone.

 

[tweezy]

and thanks for the help everybody i just want to make sure my decision is the right one before i act on this.

 

[growsjoe1]

tweezy
Again a pic is worth a 1000 words that being said you didnt mentions what kind of soil or any amendments you put in ur soil or if the soil has enough dolomitic lime to buffer any feedings reguardless of the ph feed to the plants. Soil with enough dolomitic lime(2 tblsp per gallon) has great ph buffering capibilities and plenty of cal and mag for the entire grow.
So whats in your soil make up and have u a pic.

Run down your soil profile please and post a pic that would help all out. Most soil growers feed, water, water, feed...

growsjoe1

 

[PoopyTeaBags]

next time they need a watering... you need to flush them with 6.8ph water at about 700ppm's.... you need to flush UNTIL your water that comes out is 6.8 and about 700 ppm's

if its super low or super high ph then you can lower the ph you put in a couple point to try and get your ph set right alittle faster... your ph in your pot is probably high causing salt buildup and not letting your plant take up nutes correctly.

 

[sso]

easiest way to fix that (and probably quickest(and i personally dont use anything else)

bit of your own urine (like a cup or 2 per plant (teacups) then water as normally. (till you got some runoff)

(though since its 5 gallon, might want to use 3-4 cups per plant(unless its dark urine, then 1-2,depending on darkness)

if you gave them enough, then you should see healthy plants in maximum a week, (2-3 days usually)

but if you are fuzzy or squeemish, then go with the other guys advice