??Guidence would be appriciated?!

hi everyone, i was hoping someone could give me a little advice.

i have 3 seedlings currently 1 week and 1 day old. one of them has been out in the greenhouse and is progressing nicely. the other two however are been grown indoors; one has got yellow lower leaves and the two upper leaves are starting to point upwards at the tip, the other is now starting to get yellowing lower leaves.

initially these plants were growing on a 400w hps light but i swaped to a mh light about 4 days ago. in addition to this i have recently changed from using ph balanced tapwater to using rain water following the initial signs of yellowing leaves. these seedlings are not currently on any form of nutrient and i am stuck on what to do.

the light is mounted approx 1 1/2 foot away from the plants and i don't think its too hot up there. however with no thermometer i can't be certain, although its about the same temp as the greenhouse. (i live in britain so currently outdoor temperatures are peaking at 20 degrees C).

Cheers

I would actually use floro's or cfls for the first week or 2 and introduce the mh around the 2 week.....

i haven't got one at the moment. would you reccomend me changing back to hps untill i get one?

place ur light a little closer..maybe 10-12inchs.....place a fan near to keep heat down near plants

i wouldn't move my lights any closer. ambiant temps are what you should worry about.. its simple do a hand test.. put your hand right on top of the plant and if its to hot for your hand then its to hot for your plants.. what type of soil are you using? if your tips are curled up towards the light it maybe to hot, if the whole leaf is pointing up it might be the MH putting out the proper spectrum and your plant loving it.. got any pics

18 inchs is kinda far away for a week old....... with a fan blowing bringing in fresh air. his ambient temps shouldn't be that high. .....hand test would show he can put it wayyyyyy closer but that still may be too much for that seedling... 10-12 sould be fine.....

ok move it as close as you want. If its to warm for your hand it will burn them up.. i don't know what type of hood you have your light in so i don't know how hot it get and how many inches is a safe distance. i just noticed the pics you posted.. they looked ok to me but im almost blind and they were blury. let'em go a few days and watch the new growth. jmo

At the current height using the "hand test", the temperature seems fine. The whole leaf is pointing upwards but the tips are curling even more.

These pics are todays update. The smaller one looks nearly dead with black on the underside of the leaves. the larger one has got even more yellow on the lower leaves, the same symptoms as the smaller. The growing medium is rockwool that was soaked prior to planting.

I don't know if this extra info will give any further clues of what is happening but two other germanated seeds didn't come through the surface of the rockwool under the same conditions. the roots turned black and have been stunted.

Thanks for the advice so far guys / girls

whats the ph of that water?????

within recommended range, i really don't think its a ph problem, although i'm not sure if the damage was done by using tapwater initially. we aren't on main supplies and rely on a borehole outside. the water is then pumped and treated by a machine under the stairs that requires salt to clense the water. maybe the sodium chloride (salt) in my tapwater is too high in salts or chlorine. the tapwater definatly does not react as much to ph up and ph down as rainwater which may suggest a higher chemical content. without a ppm meter its hard for me to tell.

i'll keep watering them with rainwater to see how they progress. as i said earlier, the plant in the greehouse is doing fine; rainwater is all its had.

Cheers