Ph problem/question

Hey guys so I'm on my first ever grow and I'm 4 weeks into flower and my 2 plants leaves are starting to go really yellow and curl/droop down as well the leaves veins are a dark red color. I know this is probably nitrogen deficiency because I haven't been feeding much at all lately because I nute burned it a few weeks back so I've been takin it easy on the nutes. Anyways, today I fed them with 1100ppm of mega mass blend (2-0-0) and mega mass grow (1-2-5) and ph at 7. Normally my ph would go in at 7 and come out around 6-6.2 but today it went in at 7 and came out at 6.8 and I'm wondering what this means. I know it's suppose to drop 3/4 to a full point so is something wrong? I want to save my plants before they get too far gone! Thanks.

Your 4 weeks into flower and the P&K levels of the nutes are that low......it's time to bump those up to around 10. at this point you might consider a 10-10-10 nute and it should help you finish out ok. Next grow you should consider going organic! Mix this soil formula up and simply water it. Maybe a little top dressing with some high P&K guano late in flower, but for just starting out in organic you could just water and try new things next grow. Nothing like water and walk away!
http://forum.grasscity.com/organic-growing/1116550-easy-organic-soil-mix-beginners.html

As for the pH....what are you in? soil?
Metering the outflow is not really telling you anything more then the pH of the outflow! Soil self regulates pH. You might add a cpl of TBL of dolomite lime to the top of the soil to help regulate the swings in pH. You should add some active bio's to the soil for the same reason, because synthetics are HARD on the living things in the soil and they play a BIG role in the regulation of soil pH!

Healthy soil will act like this. You water and the pH will swing one way. as the soil drys back out it will swing back the other way.

Water/feed with the solution pH at 6.5 and forget it.

For active bio's in soil,,,look at
Hesi's Power clean
Canna Zyme from Canna
Zyme from Cyco

These all work well for what you need.

Wow thanks for the response dr. Who that was very helpful! Yes I'm going to go to the hydro store today and pick up some heavier nutes, look for a 10-10-10 like you say. I'm curious tho, how does ppm of the nute relate to it's npk value? The higher the ratio will it take less of it to get higher ppm or something? Also I had no idea soil regulates it's ph, and the reason I'm ph 7 is because my hydro store told me their soil is acidic and I should water with a more basic solution to level things out, is this ok? I'm interested in growing organic as well but I had no idea how to go about it, I'm gunna look over that thread you linked in your response. Thanks again!

PPM of any nutrient tells you the concentration of the nutrient in your solution.....your in soil so you don't need to do any ppm checks, just simply use the nutrient at the makers listed amounts and times.
Hmmm, acidic soil,,,,add the dolomite lime to the soil surface and just pH the water/feed solution to 6.5 and do your watering with that. The soil will settle into a good point value for your plants.

To really learn about organics read this. The chapter on Teas is worth the price of the book.
http://www.amazon.com/Teaming-Microbes-Organic-Gardeners-Revised/dp/1604691131