Dried Leaf Tips.. Early signs of Heat Stress???

up untill a couple of days ago there werent any problems with my 3weeks old babies, but yesturday morning i noticed the leaf tips had started to dry out, im wondering if this could be heat stress as i dont have a thermometer just yet...
there in canna coco soil, get ph6.0 canna terra vegga water mix.. within the last week ive changed from boiled and cooled tap water to rain water. and im using 2 CFL's.

i have good air movement and extraction, thery get fed every 2-3 days.

does anybody know if the change from hard water to soft water could cause this, or does it look like heat stress?

ill get a thermometer asap so i can post the temps but if anybody has any ideas please reply.
Thanks
Giz

ps, 4 are 3week old, 2 are 3month old but was in a mess when i got them, now rehabilitated.
2 at 3month are the two closest on pic of all, one on right is bluecheese all other 5 are like a blueberry X Jack x something, strained by a local kid who called em, Livers!

thank you for the quick reply, your comments are appreciated. ill ponder on the watering side of things but the pots do feel light when i feed again, and i repotted the 2 big ones 2days after watering and the soil was dry throughout... but perhaps im not feeding them enough? how much water would you give each plant?
At the moment they get about 1pint each and i feed it in round the outer edgeof the pot so the roots have to grow for it, this has made them produce roots quicker and more even than i have gotten before.

Pictured is the bluecheese root system when i repotted it, id changed the soil only 2weeks prior as the person who had them before me had used some sand based shit. so what you see had developed in 2 week..

sorry when i say water/ feed i mean water + Canna terra flores feed

one of the plants seems to be getting worse..
please check the pic, can anybody tell me if theres a problem or are they just a couple of old leaves that need pulling?

Those tips are your first sign that you're overfeeding. Rather than reduce frequency of feeds, reduce concentration -- try cutting your concentration by 1/3 or 1/2 and watch the new growth for absence of those dead tips (the ones already dead will never recover).

Water thoroughly until you get a little water out of the bottom of your pots. That little excess will carry out excess salts. Feel the weight of that fully watered pot and burn it in your brain. Let the pots until they feel light; probably about 3-5 days for the plant / pot size balance you have there. But don't let them dry too much - letting a pot get dry concentrates the soil salts - you want to try to keep a consistent water / nutrient balance in there.

The overfeeding that started the tip death will take a few days to work through. That's why they're still getting worse; that will pass quickly. Overall, they look great; should pull thru easily.

ok, thank you for the quick response..
so let me just confirm this, i need to give them more a pint each because i didnt have any run off before, but instead of mixing 50ml feed to 10litre water i need to mix 25ml feed or less..?
also i was boiling my tap water because it contains lots of lime scale and without a boil it leaves the top soil white.. its not rained in a few days so i will have to go back to tap water.
i havent fed them for about 3 days now so the soil is dry about 2inch / 50mm deep and the pots are feeling light, would it be a good idea to feed today or leave until tomorrow?

thanks for the help, +Rep!

Those look like 2-gallon (8-10 litre) pots or so? If so, it will take at least a quart of water to produce runoff - a pint is too little. If they feel light right now, I'd water now until you get runoff.

I wouldn't go any lower than 25ml. It's a minor overfeed -- don't want to swing too hard the other way.

The level of lime scale your water leaves is a concern; that implies a lot of extra salts going in and may be more at fault than your nute concentration. I know some high carbonate waters have 4-600 ppm of total dissolved solids - that's a lot of extra ions to put into a container plant. Usually tap water is fine but, in your case, you may want to consider investing in a water filter to remove that.

a water filter is something im planning on but money is tight at the moment,.. i got sacked from my wood work job because random drug testing found THC in my system.. so no work n very little money..
im hoping to get a 600hps also ready for flower thatll be in bout 3-4 weeks i think so need to get saving.. im having to smoke 0.5g per day rather then my regular 3.5 ... its not good!

is a quart, a quarter of a gallon? sorry im in the UK we have different measurements

i have 3 different size buckets due to re-using old having to get some new..
3 of them are 8litre
2 are 10litre
1 is 12litre

All those sizes will take more than a pint per watering - about a quart should do it.

ok, thank you

gizanoz said:

i have good air movement and extraction, thery get fed every 2-3 days.!

Click to expand...

Slow down on the feedings, once a week is fine.

+1 on using at least a qt (liter), of water rather than a pint. Always water to runoff.

Wet

there wasnt any heat stress, just my paranoid self lol..
check out my babies now..
the 2 at the front are the two older ones that have been messed around for light by the person i got em from.. because they have seen 12hrs light then back on 18 there leafs have curled... theyll be budding soon!