question concerning lucas formula and low ph.

I am currently on my 3 rd week of flowering in promix soil with a co2 supplemented sealed room. I just flushed my soil with ro water, I was using the fox farm schedule and it was just too hot. I'm going to the Lucas formula and I mixed flora nova bloom with ro water. Ppm is at 1350 but my ph is at 4.4, should I use ph up to bring it up because that would raise my ppm in the 1700 range (i just did this) but Lucas stated in the ask Lucas thread that you want your feeding run off to not exceed 1800, if it does flush until its 1300. I'm afraid that I'm going be flushing every other week from feeding with a solution in the 1700 range.

What should my ph be in my nutrient solution and what should it be in my run off?
Lucas stated you want feeding run off at 5.5, this seems low to me, because once the solution dries the ph will lower in the soil. And 5.3 in soil is about the lowest you would want, about 6.3 sounds right to me. Any advise would be greatly appreciated. Thank you

!!!!!!!Bump!!!!!!!!!

!!!!!!bump@@!!!

From what I have been reading, there is little in the way of a solid understanding of the best way of using Promix. I recently posted a question about whether it is better to use a soil-based or hydro-based fertilizer, and also got no response.

In terms of ph, here is a link to the best discussion I have read on the issue:
http://www.icmag.com/ic/showthread.php?t=121511

As you will see, the debate focuses on a Ph from 5.2 to 6.8-- although most see the range as 5.4-6.4. I think 4.4 is too far on the hot side of things.

I have been running my grow with FF nutes at 6.4, and they seem to be doing fine. I'm thinking I want to drop closer to 6.0, though.

IMO, the variables that determine best Ph are: Amount of perelite in the mix, amount of dolomite lime added, feeding style (every other watering or every watering-- also amount of runnoff per watering), and maybe organic vs. chemical. Lime is the wild card here, because it can start to disolve out of the Promix over 6 weeks or so.

Once I have one or two solid generations in Promix, I plan on running experiments adjusting each of the variables mentioned in the last paragraph. It might take a year or two for me to have anything conclusive, though.

you are not in soil tho. you are in soiless. the ph is like hydro. you are using hydro nutes. your medium is inert. peat moss is acidic too. do what lucas said. remember the effects of high ph wont show until flower when the P lockout hits. Now they prob look fine.

tea tree said:

you are not in soil tho. you are in soiless. the ph is like hydro. you are using hydro nutes. your medium is inert. peat moss is acidic too. do what lucas said. remember the effects of high ph wont show until flower when the P lockout hits. Now they prob look fine.

Click to expand...

So do you recommend 5.2 then?

I recomend using 5.8 nute solution. Then I recomend checking the runoff. If it is high then I recomend using a lower ph solution. The reason you need this lower ph is because peat moss has no soi l qualities or minerals or web or nada. You are giving the plant all the micro and macro elements it needs in a liquid. It is hydro. So the ph chart you follow is the hydro chart. Unless over 8 you prob wont notice anything worng until after a few weeks of flower. Lucas shud have had some good advice for you. Careful about watering too much or with too much solution. It still needs to dry out like soil. This should change your perspective.

Thanks Tea,

I'll do some reading up on Lucas. It is odd though, most folks recommend adding lime to Promix soiless-- that would seem to work against holding a 5.8ph. I gotta work this out before this weekend when I transplant my ladies.

My appologies to Guff if this seems like a thread hijack-- the info is in line with the question you raised, though.