yellowing leaves :bleh:

[an_arrowfromthesun]

Ok so I'm pretty desperate right now have two new plants in the early second week under a 400w hps, though they are pretty close to the light. I'm using gravel as a medium, and Amsterdam Indoors for the nutrients. My tap water is usually high in alkalinity in the 9.0 - 8.0 scale. I usually have been bringing it down with phosphoric acid. I usually keep the res at 5.8 - 6.0ph. I haven't had a problem with ph fluctutation this time as i'm using gravel instead of clay but the same problem on my plants keeps appearing! FU** The oldest and first leaves started appearing with yellow spots on the leaf tips and then those whole two oldest first leaves on the plant started curling down and browning. It hasn't affected much yet but I would like to stop what is affected asap it seems to be along two or three lower leaf margins and the oldest first leaves tips any ideas would help greatly. One plant also seems to be way more affected then the other, it seems to be the indica/afghani and the sativa seems way better off, the indica is also the closest to the light.

[SukonmiSkunk]

how many times a day are you watering it? and what is the TDS PPM

[an_arrowfromthesun]

Hey i'm not sure about the tds hey actually i don't have an elec scanner only ph for now but i haven't read into the tds scales at all, i'm watering the plants only twice a day atm i thought maybe it could do with the high alkalinity maybe it would be the calcium stopping the potassium in the water? Is there any soultion like a foliar feed for yellowing older leave tips/margin thingos? Thanking you skunk.

[Ozzy420]

When i 1st started growing indoors i used Amsterdam Indoors my self and dident have a meter to test how strong it was but when mixing up 100% full strenth as it says on the bottles i found i got a lil bit of nute burn, so i backed it off to about 80% strenth instead of 100% and keepet my ph at around 5.5 and all was well.

[SukonmiSkunk]

if youre using gravel, and only watering twice a day... thats a 18/6 light cycle yeah?? then its probably a nutrient difficiency.. try watering more often.. as gravel wouldnt really hold a lot of nutrients.. if your ph is at 6.0 then that is ok.. aim for about 6.3... but I would be watering every 2-3 hours ....

[snowbuds]

it a bit out there! but, sure your lights not to close. (30cms) from the tips.

 

sounds like you have most factors under controll, except the td scan.

like oz said, cutt back the strength of your nutes.

 

i use ph addjusted water for the first week of grow with a couple of waterings of b1 (nutriboost) then half strength dutchfest for the second week, then full strength for the rest of the grow.

 

all the best with it,

[an_arrowfromthesun]

Thanking people for the help I have come to a couple of bright ideas now, I think the two plants might of still been going through some sort of defficiency with the nutrients not being cycled enough to the plants only twice a day, because they aren't in the seed stage at all now, but the ideas about half strength and some grow liquid for future seedlings would be good to mull over, I just whacked them in a couple of perlite filled/lime cups before n let them be under the hps for ages, as I said before they are two weeks along but they are two weeks along in the veggie stage. They seem to be taking the amsterdam indoors well, just hoping i won't make what will be left to bud a harsh smoke from now on n I can finally smoke some of my own gear this time not "just" everyone elses.. n make it through to flower finally.