400w hps height above 18 day olds

New to indoor and when searching for height on 400w hps over plants18 days old i find so many different answers from 12" to 3ft.
I have mine a little bit under 2 and a half feet away and its slow progress but they were old seeds because im unsure about purchasing seeds over the net.
I also search for plants my age and compare there growth rate with mine and i seem a little behind.Ive changed from average organic potting mix to richgro peat moss on Thursday and could already see the plant wasn't as droopy this morning and my ph is about 6.3 but was closer to 7 with the other soil so im hoping for a rebound

I would keep the light at 3 feet for a while.

There's a big gap between too much and too little light, and too much will royally fuck up your plant at that age

You don't need the HPS yet.
Get a couple regular light bulbs and put them about 6" above your seedlings.

Feed them

.Smoke said:

You don't need the HPS yet.
Get a couple regular light bulbs and put them about 6" above your seedlings.

Click to expand...

Had them under them 2 of these which were my fish tank light but one blew on Tuesday so i put them under the 400 watt till i go shops on Saturday and purchase more,

3 ft as suggested above, if you don't want to use another light for early vegging, and temps aren't a problem.

lurchin1 said:

Had them under them 2 of these which were my fish tank light but one blew on Tuesday so i put them under the 400 watt till i go shops on Saturday and purchase more,

Click to expand...

Those don't really put out much light...

Tolerance Break said:

I would keep the light at 3 feet for a while.

There's a big gap between too much and too little light, and too much will royally fuck up your plant at that age

Click to expand...

Had to talk myself into it but i went 3ft 5 days ago and yeah with new soil and a feed of root stimulator and a light nutrient feed its booming,thank you.

Buy luxmeter and find good lux ranges on internet or guys from here. Then you can hang higher or lower easily with reading that meter. If you don't want to buy there is good applications can be used with smart phones.

My 4 week old vegging plants are under 1000w hps with 51-52K and it's 60cm away from canopy. I am using cooltube btw.

DarkLordMelkor said:

Buy luxmeter and find good lux ranges on internet or guys from here. Then you can hang higher or lower easily with reading that meter. If you don't want to buy there is good applications can be used with smart phones.

My 4 week old vegging plants are under 1000w hps with 51-52K and it's 60cm away from canopy. I am using cooltube btw.

Click to expand...

Ordered a cooling tube arrives Monday and ive lowered my light to 2 and half feet,i think its rebounding fast

DarkLordMelkor said:

Buy luxmeter and find good lux ranges on internet or guys from here. Then you can hang higher or lower easily with reading that meter. If you don't want to buy there is good applications can be used with smart phones.

My 4 week old vegging plants are under 1000w hps with 51-52K and it's 60cm away from canopy. I am using cooltube btw.

Click to expand...

At what age did you put plants under hps and what height did you start at,cheers too

lurchin1 said:

At what age did you put plants under hps and what height did you start at,cheers too

Click to expand...

Started with HPS because had some problems with MH bulb during shipping. I always measured lux. Started with 7k and increased week by week. Now i am at the edge probably. More than 60k is not recommended but i am keeping it at 52K now. No need to risk Will increase when i flip.

DarkLordMelkor said:

Started with HPS because had some problems with MH bulb during shipping. I always measured lux. Started with 7k and increased week by week. Now i am at the edge probably. More than 60k is not recommended but i am keeping it at 52K now. No need to risk Will increase when i flip.

Click to expand...

30k im at and thanks for the input

lurchin1 said:

Ordered a cooling tube arrives Monday and ive lowered my light to 2 and half feet,i think its rebounding fast

Click to expand...

Keep in mind a cool tube restricts light output compared to an open bulb
You will be able to get closer but you lose output

lurchin1 said:

Ordered a cooling tube arrives Monday and ive lowered my light to 2 and half feet,i think its rebounding fast

Click to expand...

Keep in mind a cool tube restricts light output compared to an open bulb
You will be able to get closer but you lose output = lumens