5-1/2 wks in . . . K deficiency?

[ir0nLung]

like the title said im at day 38 and im seeing some tip and leaf edge burn. ive been doing this a long time but deficiencies/toxicities still confuse me at times. the ph has been between 5.4 and 6.1 for the duration. ec has never exceeded 1.18. they are in a recirculating dwc, roots look platinum. buds look good but not as fat as i hoped for this stage. burnt tips always make me think im feeding them right to the max of what they need, but the edges are showing some burning/bronzing. is this a potassium deficiency? calcium maybe? is it possible to overfeed at 1.18 ec? in my stand alone units i commonly run 1.5 during this stage but i dialed things back for the rdwc. any thoughts from you herb scientists out there would be greatly appreciated.

(using tap water, canna aqua flores, pk13/14, canna boost 3/4 strength. maybe 1 ml per gallon of cal mag)

 

[ir0nLung]

just to be clear its not so much the discoloration of the leaves that i'm concerned about, its the fact that my flowers are not filling in the way im used to seeing. i thought that it might have been possible it was a lack of potassium, but maybe its not a nutrient problem, im stumped here. i have worked with dwc for quite a few years, but this is my first run in a home made "uc" style setup. the system seemed to absolutely kick ass the entire way, but im familiar with the two strains pictured (chronic, blue dream) and have always had fuller flowers at this stage. with no co2 1.18 ec should be in the ballpark of what im shooting for right? any thoughts as to the cause of this are appreciated.

 

[Seamaiden]

I need better pix to really say.

 

[ir0nLung]

i'll try and take my time and get some better ones 2nite. im having trouble capturing the problem in a picture, the one on the left actually looks kind of good in the picture, but there is definitely something awry with these.

 

[leadsled]

Looks like maybe toxicity, it is possible to overfeed at 1.18ec. All strains are different.

When you see the burnt tips you are already past the point of overfeeding imho.

Bigger pics would help, but you do have a slight curling down of the leaves, very dark green, and also burnt tips. all leading to suggest to drop ec, see how they respond they adjust.

have you tried feeding at 1/2 strength to see if they bounce back?

There is not a set number for ec, you have to watch the plant and adjust accordingly. The ec will also rise and peak around 30-40days, then you can start slowly tapering the ec till harvest.

sometime less is more.

 

[ir0nLung]

i wasn't really entertaining the idea that i could be overfeeding at less than 1.2 ec, (hell, my dumb ass was considering juicing them up to 1.5 lol) however leaf twist and burned tips seem to be substantial evidence that overfeeding locked out the k resulting in leaf edge bronzing and flowers not properly filled in? does this seem like the case? is it possible to have an ec that is a fairly low number but still lock things out because of the ratios fed. like maybe i should have lowered the AB and given more of the boost and pk 13/14 or vice versa to arrive at that number instead of just going 75% on everything? or maybe things mix so well and are so available in that style of system that i should peak out at 1 ec or so. i have a 6 unit system that is 21 days behind this one with a current ec of .9 and everything looking tits so i do not want to repeat my faulty feeding. im begging for your thoughts here!!

 

[Seamaiden]

Is this soil? I'd say that you shouldn't be chasing numbers, look at the plants. These girls are saying they're being overfed, yes. It's also important with regard to your reported pH ranges. If it's soil, that pH is too low, needs to come up a full point.

 

[ir0nLung]

they are in a home made uc style system. it just baffles me a little because in my solo units its not uncommon for me to get the ec up to 1.5 or so with no signs of toxicity.

 

[ZombieSlave]

Yours looks like your over feeding. I would flush and start over. asap.

so in real UC system im being told to use a 30% strength solution per whatever the calculator says.

so if you have 9 buckets @ 13gal you probably will have around 75gals of water, you take 30% of 75gals = 22.5gal.


plug 22.5 Gallons into your calculator and I would take whatever that comes out to and cut that in 1/2 or 1/4 depending how sensitive your plants are add slow over the week. week 1 im seeing you should stay around 550 ppm (.005) flower.

otherwise your going to just totally cook your plants like i did.

 

[ir0nLung]

zombie, you're right about the over feeding. im gonna drain the system 2nite and fill it with .9 ec solution and see if i can squeeze a lil more growth outta these things. i was at 550(.8ec with.68 conversion) during week 1 of flower and slowly increased up to 1.18 in wk 5. i actually thought i was underfeeding because i was seeing what appeared to be a potassium def, but once ledsled pointed out to me that you can overfeed at 1.18 it became clear to me that this is the case. i thought i was doing the less is more thing but i think an ec of 1 is where im limiting myself from now on when no co2 is in use. im not sure what you meant with the .005 thing.

 

[Seamaiden]

Shouldn't a UC be treated like hydro? And if so, wouldn't that mean the pH should be ranging from around 5.2-5.8? That's how I've run my perlite hempies, in that range. They're showing definite signs of unhappiness with their current pH parameters.

 

[ir0nLung]

5.8 would probably be ideal but would be a pain the the ass to keep there at all times. i have read uc guys saying that they let their ph swing all the way up to 6.5 without issue. i dont think its ph. when the pics were taken the ph was 5.6. they didn't show any signs of unhappiness until i pushed the ec up. i should have kept them around 1 i think.

 

[leadsled]

That is correct, 5.6 to 6.5 is a safe range for hydro.

If underfed, easy to add more nutes, once overfed you can't reverse it. You can try and minimize further damage.

Check your ec and ph that will tell you if your giving the plants the right amount of nutes.

Basic Example of how to do this and apply it to your grow:

ph rises and ec drops. plants are feeding on nutes. all is good, can leave at same ec.

if you want to bump them up, you can slowly increase the feed. of course keep an eye on the plants and make sure they are happy!

ph lowers and ec stays the same or rises. They are not taking in nutrients. Go to 1/2 strength, watch them recover. Then keep your ec where the ph rises and ec drops.

That way you are reading your plants and steering them in the proper direction.

I find this technique really helped me to dial in the nutes and improve my grow.

The technique also applies to soiless growing. That is where many hydro growers have an advantage over growers that have never dabbled in hydro.

Hope that helps.

 

[ir0nLung]

you're right on the money led. shit was going so well i thought i was on cruise control. i had been sticking around .8-.9 ec and ph was rising ec was going down and i got greedy and juiced em up a little too much and didn't look at em for a few days. big mistake. now i'm likely sentenced to a very average harvest in a couple weeks. at least it was only a 4 site system though. i have some other larger systems a few weeks behind that i'll peak at 1.0 ec.