Plant problem

[smileibiza]

I would like some advise.

-indoor
System NFT/hydroponic
-specific medium - rockwool

-Hydro/NFT system type


-Water source rain water passed through uv anti bactieral filter
-Water pH 5.8
-Age of plant 10 days veg & 1 week flowering
-Type of fertilizer General hydro 3 part (flora gro, flora micro, flora bloom.
EC. 1.4
-watering cycle 15min on 45min off
-Lighting source and distance from plant HPS 600w ajustawings reflector with spreader 30cm from plants
-Temperature 28deg day 18deg night(both day and night if you are running a dark period)
-% Relative humidity 50%
-Lighting schedule 12/12
-Type of ventilation your room has 3000m3 extractor and ventilation fans

smileibiza Reviewed by smileibiza on 02-29-2008. Plant problem I would like some advise. -indoor System NFT/hydroponic -specific medium - rockwool -Hydro/NFT system type -Water source rain water passed through uv anti bactieral filter Rating: 5

[smileibiza]

some more pics
general yellowing of lower older leaves with some plants with leaves curling down. Upper leaves green
yesterday sprayed with 8/8/6 fertilizer 2 ml per liter
Composition : N 8%, P 8%, K 6%, B 0.002%, Mn 0.05%,
Mo 0.002 %, Zn 0.05 %, Aminoacids 5%

[Weedhound]

Wow....those look like some sick plants. Somehow they are burning. I don't really understand the rain water and UV filter so I'd start to wonder about your water first off. What's the ec of it? Rain water really isn't as clean as some people like to think and I'm not sure about the bacterial thing so I can't comment on that. id also wonder about enough calcium and magnesium from rain water but again, am not sure.

Until you figure out what's going on I'd stop ALL nutes and I'd go back and recheck and recalibrate your ph meter (or at least check and make sure it's calibrated correctly)
I would put them on ph correct water until you can pinpoint the problem. Rockwool is known for it's ph issues. Maybe the ph of yours is abnormal.

From the pics you've provided it honestly looks like everything is wrong. They look overnuted and nuteburned AND they look like your ph is off. That brings me back to wondering about your water. Have you used it before with success?

Hope you figure it out.

Good luck.

[Weedhound]

Also I don't use rockwool but aren't you supposed to water it about twice a day or something to avoid overwatering? That's just a guess on my part.

[smileibiza]

I recalibrated Ph meter it was reading 7.5 when it should have been reading 7.
I was growing with earth and I decided to try nft with rockwool as i've read of amazing yealds with it.
I did one previous grow with rockwool and was advised to keep watering system on 24/7 which I did without problems.
I've since spoken to others and one recomends 12hr on with lights and 12 hr off on the night cycle. the other recomends 15min on 45 min off, throughout the 24hr cycle which is what I have now.

Is it possible to rinse rockwool with H2o2 ( hydrogen peroxide) solution to kill any bacteria? If so how many ml per litre?

[stinkyattic]

I'm going to let Weedhound answer the peroxide question, but I'll tell you a little about rain water.

As water passes through the atmosphere, it picks up all sorts of stuff... some of it not so good. In areas that are 'downwind' from a weather-pattern perspective of a pollution source (industrial area, coal-burning power plant, or even a city), rain will have dissolved Nitric and Sulfuric acid in it. The ratio of N:S compounds is directly correlated to how much of the pollution comes from gasoline burning versus coal burning sources. What looks like a Nitrogen overdose on your plants may very well have something to do with this. Just out of curiosity, what is the pH of the rain water when you first test it?

The second, and arguably even more important problem, with rain water is the complete lack of dissolved MINERALS in it. Surface water (lakes and streams) and groundwater (wells and aquifers) both contain significant levels of dissolved CaCO3, the primary constituent of limestone.

So why is this important? For a couple of reasons. Plants need Calcium to grow properly. It is one of the most important parts of a plant's 'diet'. It is considered a secondary nutrient, but it is so important that if you are growing hydroponically from a source other than fairly hard tapwater, you absolutely MUST add a calcium supplement such as CalMag Plus.

What you have there looks to me like a Calcium deficiency and a Nitrogen overdose. You're going to want to switch your water source away from the rain water, and start using a calcium supplement. The roots look white and healthy, so I would not be overly concerned with peroxide at this point, although you might want to add a beneficial bacteria culture to your nutrient regime. SubCulture is one to look into.

Hope that helps.

[smileibiza]

Thanks :thumbsup::thumbsup::thumbsup:I was cosidering to add calcium but was not sure if the deficiency was because of lock out of nutes and did not want to make the problem worse. I aslo thought spraying with balanced fertilizer would be enough.but i now see it didnt have any calcium! The EC of the nute spray was 1.4 EC maybe it was a bit strong?
With regard to the rain water its Ph is 7.0-7.1 with an ec of 0.10 so not much disolved salts.
In the summer when I run out of rain water i get a truck full of well/ground water EC 0.9
Could also do with some advise on watering frequency
:thumbsup:

[Weedhound]

I dont use rockwool myself but here is some info on it. Hope it helps..

Hydroponics - Rockwool as growing substrate

[Illusion]

listen to Stinky about the rainwater, i've read all that before, but all i could fathom up as a response was "Don't use rainwater, its bad!"

i wanna be smart :clap::detective1:

[smileibiza]

I don't have much choice, the tap water has an EC of between 8.5 & 13 so its impossible to use that. i could get water delivered by the lorry load but would have to keep it in the tank with the rain water catchment. alot of hydro guys use RO(reverse osmosis)water which also has no calcium etc. So i thought rain water is fairly similar RO water has EC 00 my rainwater EC 0.1. I use Uv sterilization light to permantly alter DNA of bacteria to stop it reproducing. I don't know what else to do.