Grow Mediums Lucas Formula PH Confusion

[nben]

Hi all! Been looking into the Lucas formula and have found a couple threads on it but nothing seems to answer my questions.

I have a RO filter that should be arriving today. Have the GH nutes for the formula already. Probably won't be starting with it until my DP Auto Blueberry has finished but I am stumped...

So from what I have read with the formula you get a PH at a perfect 5.8. I don't understand how it stays this way after you start adding in plain RO water, as the method instructs. The way I read it if, for example, you start with a four gallon reservoir after you top off with the equivalent of four gallons RO water you switch out the whole thing and start over with fresh nutes. Does the PH keep a constant level even with the top offs?

Having a really frustrating time with my filtered well water so this method interests me.

I also read differing things on RO water in general. I see threads that say RO water is great for correcting PH swings and then I read that all RO water does is create PH swings. Then I read that you should buffer the water with 20% tap water so the PH won't swing... I'm at a loss here

Any assistance would be really appreciated! Just trying to learn what to expect before I actually get the filter up and running.

 

[Muddy]

I'm not real familiar with the Lucas formula but I do know some about using RO in hydro. RO will remove almost all the minerals from the water, so it's up to the grower to replace them. This is usually done by using a calcium/magnesium supplement. You'll need to know the PPM/EC of your RO and then add enough cal/mag to raise it to between 100 - 125 ppm, or about .2 EC. That will help to buffer the RO. Do this before adding your nutrients. After adding your nutes then adjust the pH. Some people do add in tap water but there's a couple problems with that. First you would need to know the ppm/EC of your tap water, then would need to add just enough to raise the ppm/EC to the proper level. Also, tap water usually contains either chlorine or chloramine, which can be harmful to the plants. You would need to know which is used. If it's chlorine, the tap water would need to be bubbled for about 24 hours so the chlorine can dissipate. If it contains chloramine you would need to boil it for two hours to remove it.

 

[nben]

Thanks Muddy!! I actually live in the country so I have a well. My water is high in Calcium and Iron. Presently TDS runs at 340...

Is there a calculator or formula online that I can find to see how much I should be adding in?

Thanks again for all your help

 

[pop22]

I'm not real familiar with the Lucas formula but I do know some about using RO in hydro. RO will remove almost all the minerals from the water, so it's up to the grower to replace them. This is usually done by using a calcium/magnesium supplement. You'll need to know the PPM/EC of your RO and then add enough cal/mag to raise it to between 100 - 125 ppm, or about .2 EC. That will help to buffer the RO. Do this before adding your nutrients. After adding your nutes then adjust the pH. Some people do add in tap water but there's a couple problems with that. First you would need to know the ppm/EC of your tap water, then would need to add just enough to raise the ppm/EC to the proper level. Also, tap water usually contains either chlorine or chloramine, which can be harmful to the plants. You would need to know which is used. If it's chlorine, the tap water would need to be bubbled for about 24 hours so the chlorine can dissipate. If it contains chloramine you would need to boil it for two hours to remove it.

Sorry but, you could boil your water for a week, it won't get rid of chloramine! However, there are things you can add to the water
( I think lemon juice may have been one, you'll need to look it up ) that will break the chemical bond of the chloramine, then it will dissipate.

 

[nben]

Luckily I don't have any additives like that in my well water! I can't even drink water when I'm in a city I've got so used to not having any Chlorine taste haha!

Edit: Even being around a pool burns my eyes

 

[Muddy]

Thanks Muddy!! I actually live in the country so I have a well. My water is high in Calcium and Iron. Presently TDS runs at 340...

Is there a calculator or formula online that I can find to see how much I should be adding in?

Thanks again for all your help

I'm not used to dealing in TDS, even though my Hanna Combo meter does measure it. I always use PPM. So I just went out to the garage, drew a gallon of RO, added some cal/mag and did comparison readings of TDS and PPM. The PPM was 114, the TDS, 230. If that hold true across the whole range, that would mean your PPM is around 170, which is a bit high. Generally speaking well water will have a higher PPM value, especially if you live in an area with a lot of lime stone.

Sorry but, you could boil your water for a week, it won't get rid of chloramine! However, there are things you can add to the water
( I think lemon juice may have been one, you'll need to look it up ) that will break the chemical bond of the chloramine, then it will dissipate.

It will remove it, just takes a very long time. That was a typo on my part. Two hours of boiling is needed to remove chlorine. Chloramine takes 24 hours or more of boiling. Regardless, the point is it's just not practical.

 

[nben]

Thanks again Muddy I guess my best bet with the new RO filter is just to wait to use it until I have a day off and monitor the situation and see how it reacts.

I just liked the Lucas formula because people seem to think it is so darn easy. I am not one of these guys who is tweaking their formulas or using flowering boosters. I just find what works well and stick with it. I do not want to have to go through the roller coaster ride of PH fluctuations anymore however... I get that as the plant sucks up the nutes it will change but this last ride has been terrible! No mas!! hahaha!!!

Can you tell me, as far as PH goes, in RO water how PH down reacts? Do you need much less of it in the rez than with my filtered well water? How are the fluctuations after the nute solution sits for a couple days? I'm sure this is dependent on what stage the plant is in but can you give me a general outcome?

Filtering has become a joke it seems that they are making filters different and cheaper these days. I used to just swap it out every three months (I only do one plant at a time) but now my water has a noticeable tinge to it within 24 hours of letting it sit, about three weeks after I changed the filter.

This is why I bit the bullet and put the money down for the RO filter. Even with a brand new Zero Water filter my water is running at about 7.5 PH, which is pretty high from what I have read on different threads.

Thanks again Muddy, much appreciated!

 

[Muddy]

Run about 20-30 gallons through it before you start to take readings. I found with mine that it took running that amount for the readings to settle down. 7.5 isn't bad on the pH. Mine generally runs right around 7.1 - 7.2. I'm using city water that is usually right around 8.2 before filtering.

I've not noticed a difference in how much pH Up or Down is needed in RO vs tap. If there is a difference, it's not much.

I'm not the best person to talk to about pH in DWC. I'm running RDWC with a top of res, which is quite a different animal. I've never run DWC. The top off res constantly replenishes the system. I can set the pH and ppm of the top off so that I get little variation in the actual system pH and ppm. I still get swings, but they aren't near as drastic as what I've seen in some DWC setups.

 

[nben]

Sounds like my dream setup, I will look into that

Thank you sir :tiphat:

 

[Muddy]

Here's the link for you. I'm running a UCXL8. http://cch2o.com/products.html. I just finished my second grow and am still learning.