Fert burn or K deficiency?

[AnomanderRake]

Hello growers!

This is my first post here in this great forum. I've been reading a lot and started my first grow, and until now I had no problems.

Last week two of my plants started to develop burn tips on some of my lower leaves. It quickly spread to most of the leaves, some with more intensity and others with less.

I read a lot and saw loads of pictures of problems and deficiencies, but could not deicide if this is a Nute Burn or some kind of deficiency (Potassium?). It's hard for me since I never saw any of them in real life (first grow!).

Hope you guys can help me!

Here is the Troubleshooting form followed by some pictures:

E-indoor or outdoor = Indoor
E-soil, soilless, coco, aero, or hydroponic = Soiless
E-specific medium = SunshineMix + Perlite
SCL-Anything you have added to the soil = Perlite
SCLR-Soil or slab runoff pH = 6,3
E-Water source = Mineral Water
E-Source water pH = 6,7
E-Age of plant = 5 weeks and 3 days
E-Type of fertilizer = Biogrow (Biobizz)
E-Rate of application = 1ml/L every watering, then when the problem appeared every other watering
E-Lighting source and distance from plant = 400 W HQI, a palm distance from the tops.
E-Air temperature (both day and night if you are running a dark period) = 82,5F (day), 79F (night)
E-Air % Relative humidity = 68% to 75%
E-Lighting schedule = 18/6
E-Type of ventilation your room has = One large fan taking air from the cooltube and grow, one smaller fan bringing fresh air, plus one small fan for air circulation.

Thanks for the help! :smokin:

AnomanderRake Reviewed by AnomanderRake on 05-12-2010. Fert burn or K deficiency? Hello growers! :) This is my first post here in this great forum. I've been reading a lot and started my first grow, and until now I had no problems. Last week two of my plants started to develop burn tips on some of my lower leaves. It quickly spread to most of the leaves, some with more intensity and others with less. I read a lot and saw loads of pictures of problems and deficiencies, but could not deicide if this is a Nute Burn or some kind of deficiency (Potassium?). It's hard Rating: 5

[headshake]

i highly doubt it's fert burn as it's pretty hard to burn with organics. i've been using the biobizz line for a few grows now, with no burn issues. you especially shouldn't have any issues with that application rate.

i definitely think you have another issue.

your plant looks small for 5 weeks. this is possibly related to the high humidity.

not to mention, i'm not too found of your light. have you used this before or seen decent results from one?


-shake

[AnomanderRake]

Thanks for the reply, Shake!

Good to know it's not fert burn. One less thing to worry about!

About the humidity, I have an dehumidifier inside the room and even this way I can't lower it more. Do you think this can be my problem? Which humidity should I target?

Someone said in another forum that my PH is to high and I should lower it to about 5.5 . Do you agree? (always thought that ideal PH was between 6.0 and 7.0)

About my lights, here in my country it is very standart to use it on the veg stage... Which one do you recommend?

I'm posting some more pictures of the two porblematic plants fo you to judge the sizes and the problem better.

Thanks again for the help! :smokin:

[Dorje113]

6.7 water pH is a bit too high for soilless, bring down to 6... 6.5-6.7 is ideal for soil, but soiless is lower.

If water is too hard it could be a problem.

Light is too low, they can't use so much light until they are healthy. Even then, a palms distance is very close to a 400 mh. Having the light so low right now is causing additional stress. I'd give them a couple feet at this point.

If there isn't enough air circulation it'll make things even worse, make sure you can see the leaves moving in the breeze.

They also probably won't need more food until they are healthy. They are really small for 5 weeks, so they haven't been using much nutes, but if you keep adding they will build up. It can't hurt to do a soil test and see where your pH is at, as well as if NPK is too far off...

[AnomanderRake]

Hi Dorje, thanks for the reply!

The water I'm using has a PPM of 30. I don't think is to high, right?

Thanks for the tip about the light height. Will correct.

I already tested the PH from the soil (from the runnof) and it's about 6,3. To high, right? Which value shoud I aim for?

So, should I keep giving them water only (with the PH regulated) and wait until they get better to start feeding again? Is there anything else I should do?

Many questions, sorry!

Thanks for the help!

[AnomanderRake]

Someone else can help me, please?
What you guys think about the PH?

Thanks!

[Dorje113]

Not sure about the runoff pH, but the water you give 'em should be about 6. You can adjust this easily.

If you can find a soil test kit, I'd buy it and test your current soil pH and NPK.

[Rusty Trichome]

Sure wish you folks that offer advise would give the correct advise.
6.3 to 6.8 ph for peat-based mixes. Keeping it below the low range and you will lock-out nutrients.

Soilless is a long-used term denoting any potting mix not made from garden dirt. The most common are peat moss based mixes, and are usually buffered to a near-neutral ph. Trying to lower this ph is unnecessary, unwarranted and depletes the buffers in the soil quicker. Sunshine is a peat based mix.

Then you have coco, hempy bucket, aero and hydro. Methods I do not use, but I hear they require a lower ph.

What do the instructions on the bottle say about dosages and frequency of use? Most nutrient products give a weekly schedule. (one application at recommended dosage per week) None I've come across are a 'feed every watering' formula.

Your growroom would benefit from proper lighting. Incandescents, HQI's, grow spotlights are all garbage in the growroom. Too much heat, wrong spectrums. CFL's, fluorescent tubes or HID lights are optimal. (in the correct spectrums, of course)

[AnomanderRake]

Thanks for the reply and advice, guys! :thumbsup:

6.3 to 6.8 ph for peat-based mixes. Keeping it below the low range and you will lock-out nutrients.

So, if PH and fert burn are not the problem (burned leaves), what can it be?

[Rusty Trichome]

So, if PH and fert burn are not the problem (burned leaves), what can it be?

What do the instructions on the bottle say about dosages and frequency of use? Most nutrient products give a weekly schedule. (one application at recommended dosage per week) None I've come across are a 'feed every watering' formula.

Your growroom would benefit from proper lighting. Incandescents, HQI's, grow spotlights are all garbage in the growroom. Too much heat, wrong spectrums. CFL's, fluorescent tubes or HID lights are optimal. (in the correct spectrums, of course)

That's still my answer. ^^^

Humidity is a little high for me, but I've seen worse.