PH questions

Hi,
I have a few questions for all you growers experienced in the indoor, soil growing area.
I grow in Costa Rica, obtaining canna specific nutes and soils isn't possible. However I have multiple successfull harvests here and am growing a purple kush strain from the bay area that generates about an oz per plant for me under a 400watter.
I am trying to perfect my grow though as I have been having some issues with yellowing, crispying and dying of the majority of fan leaves around week 5. I first thought it was high temps and not enough air flow but after str8ning that out I am still seeing them suffer a tad so I went out and got a ph tester. this is what I have found:

my tap water: between 6.5-7.0
water with my flowering nutes: around 6.0
soil runoff from new batch of soil (no nutes added): around 6.5
soil runoff from older plants soil (around week 6): 5-5.5

Basically how do these numbers sound to you guys? Do I need to up my PH in the water I am using, or try and up my Ph in the soil? Also Is there alternative methods to manipulating the PH? There are many aquarium shops but the gardening supply stores are very basic so any "home remedies" on manipulating PH would be appreciated

Also, what sort of affect does molassess have on PH? I assume it is not very acidic.

thanks in advance.

Hi Costa,heres a bery good thread on Ph
http://boards.cannabis.com/plant-pro...hy-how-do.html
maybe find your answer in it good luck
ps: ph 5 - 5.5 is low! can u find some ph-up

hello.
i now live in palmares and need to grow some stuff for medical reasons. can you tell me where i can get stuff for the soil like perlite, vermiculite, peat moss, ground kelp, fertilizers, etc. back home in canada we can get large bags in almost every garden centre. not very common here though. your help will be greatly appreciated.
dan