PH Query

[cloneX]

I would like to know if it is nessarry to use ph down when growing with peat based compost, as a gardening friend said that it is not the water which effects the ph but the soil. I have some experience but plants nearly always start to go yellow or limey green, so by adding ph down to my tap water which is 8 to take it down to 6.5 is this correct???

Do I need to use PH Down for my grow or is PH Down only for use in hydroponics? Plus is it ok to use white vinegar?

And one other thing what is the correct distance to keep a 400w light fromt the top of the plants. Thanks for any help

 

[grow_right]

plants can self adjust to soil/media pH. in soil/media, i never use a pH controller. peat based media is already a low pH.

a 400w lamp wants to be around 24"+ from the tops of plants. light burn can happen very easily.

 

[oscarthegrouch]

I use promix which is mostly peat. I ph with to 6.0 with phosphoric acid, and things look great. I used to veg under a 400w mh and was usually 12-18 inches above the plants. Hold your hand above the plants, if its to hot for your hand its too hot for your plants...

 

[Sat X RB]

yes, pH depends on yr soil/growing medium. acids in the soil dissolve minerals and make them available to yr plant. when the acidty is too high or too low this will unbalance the minerals available to yr plant.

6.5 is good. but what is the pH of yr mix? you need to know this or you have no base line to work out how much pH down to add. buy a pH meter to determine this. (soil pH test kits are cheaper but harder to work with if yr using pots ... ideally you needed to find out yr soil mix pH BEFORE you planted in it.)

seen on these Forums that vinegar may cause build up of slime (Flowers of Vinegar) if used constantly.

cheers!

 

[anon0988]

When doing soil based setups I just monitor the PH of the liquids I put in and it seems to work fine. I know that soil medium will have it's own base PH but I figure with as much liquids as you're adding constantly, if you control that it will average to around what you're putting in.

 

[cloneX]

Thanks for the replies, I have been using PH Down and this year they are all pretty healthy and green not limey green with yellowing leaves like other years, I think what anon0988 says must be partly right as I've no way of finding the PH of the Peat based soil I'm using, and I dont want to buy a soil PH Test Kit. I also added some Epsom Salts to the water this year which may have helped keep them Green too, (think u can give palnts some once a month, I fed some cutting with it too and they went all limp shortly after, Not Sure Why? So I flushed the very small pot with water and they perked back up)

vinegar may cause build up of slime (Flowers of Vinegar) if used constantly, Sat X RB thanks for mentioning this as I have noticed some sort of residue build up in the container that I use to mix the feed and water in, so will stick with PH Down not Vinegar.

What or where do u get phosphoric acid is it something used in the home or only bought in Grow shops? As there are no Grow Shops here and I would have to travel quite a bit to get to one, but thanks again for all the usefull info

 

[Sat X RB]

phosphoric acid is most easily available as 'rust converter' in auto parts outlets or yr local paint shop.

however you must be careful that it does not contain other ingredients such as degreaser. the ingredients AND the strength of the acid (some products are quite weak and poor value for money) are clearly stated on such products in this part of the world. don't know about yr area.

good luck!

 

[Gelado`]

Many kinds of pH down ARE phosphoric acid. I was offered a choice of two when I picked up a bottle two weeks ago: nitric (which provides usable nitrogen, and was labeled 'veg') or phosphoric ('bloom'). I went with the phosphoric since P is usable in veg for root growth and I like to cut the nitrogen out in late flowering.