Fertilizer solution stability

[dodidoki]

Due to Xavier s advices, I begun to learn more and more about slipper feeding. There was an appointment about citric acid....Xavier mintioned that citrate enchance the rate if bacterial infection....I amazed because Erwinia can t grow under 6,0 pH....So 5,8 seemed to be optimal, and i think the same as Xavier s thought, that Ca is useless above 6,5. So i made a solution, ec 500 uS, 20/20/20 npk, cao 7, mg 3,0, n urea 13%, with ro water. pH was 6,5. I set it to 5,8 with citrate. 24 later pH was 6,5 . I set it again to 5,8. Another 24 hours later pH was 6,5, solution start to become misty, ec decreased from 500 to 450 uS. I think this is why Xavier said that citric acid incease the risk of erwinia infection. There is some citrate salts, maybe ca, what precipitates from solution. Increased pH and decrease Ca is favourable for erwinia, in fact. Today i made another tank , 485 ec, pH 5,75, adjusted with HCl solution. HCl increased ec just 3-4 uS. Any thoughts?Opinions?

 

[terryros]

Citrate is used as a substrate for metabolism by a number of bacteria involved in fermentation, so maybe it is being actively used in the solution. The cloudiness could be partly from microorganism growth.

I don't want to use citrate to lower pH or the basic potassium salts to raise pH. When I make a 500 µS solution with MSU in RO I got a pH of 5.1 this morning. If I use 15% tap water and 85% RO I get to a pH of 5.8. I was surprised that your solution in RO started at 6.5. Do you see a reason for this?

 

[dodidoki]

Citrate is used as a substrate for metabolism by a number of bacteria involved in fermentation, so maybe it is being actively used in the solution. The cloudiness could be partly from microorganism growth.

I don't want to use citrate to lower pH or the basic potassium salts to raise pH. When I make a 500 µS solution with MSU in RO I got a pH of 5.1 this morning. If I use 15% tap water and 85% RO I get to a pH of 5.8. I was surprised that your solution in RO started at 6.5. Do you see a reason for this?

Thank you, i use another formula, it gives 6,5 pH with Ro at 500 uS/cm. I used to lower,but seems that cirtic acid acts with maybe ca ions forming cacitrate, what is hardly soluable and precipirates from solution, lower ca level and increase back pH to 6,5...I tried today with hcl. i made 480 uS fertilizer solution with RO, pH was 6,5, as i expected. I lower it with very few hcl to 5,75.Ec is now only 485....decreasing pH from 6,5 to 5,8 with hcl increase ec level only with 5 uS!!!! I wonder if solution stay in this state or change by any chemical process.

 

[terryros]

Thank you, i use another formula, it gives 6,5 pH with Ro at 500 uS/cm. I used to lower,but seems that cirtic acid acts with maybe ca ions forming cacitrate, what is hardly soluable and precipirates from solution, lower ca level and increase back pH to 6,5...I tried today with hcl. i made 480 uS fertilizer solution with RO, pH was 6,5, as i expected. I lower it with very few hcl to 5,75.Ec is now only 485....decreasing pH from 6,5 to 5,8 with hcl increase ec level only with 5 uS!!!! I wonder if solution stay in this state or change by any chemical process.

I think the pH of the solution only matters for the short amount of time that the solution is first in contact with the roots. The velamen absorbs the first things that hit it. If the ions are in solution, they will enter. Most of the rest of the fluid leaves the pot, depending on the medium. If all sphagnum, there will be a good amount absorbed in the sphagnum, but only the part near the roots will function. I don't think a pH change a day or two later matters unless you are talking about a hydroponic solution that is repeatedly circulating through a plant. The HCl- will potently lower the pH so not much EC being added.

I still can't figure out what it is in your fertilizer that is able to make a solution of 6.5 in RO. The basic property of Nitrate is somehow stronger than the basic properties of the other things.

Would you please look at this photo I took of the contents of my MSU fertilizer and see where the differences are with what you are using?

 

[wongwong]

Citric acid alone is enough to turn misty by micro-biomass
Ca & H2PO4- can precipitate/eliminate as CaHPO4 toward neutral pH;
May wait some time to see if urea drift back pH when hydorlyze as NH3
.....or you actually detect ammonia smell for your urea 13%......
(pH6.5 may be just alkalinzation from NH3 & cease there with partial precipitation of CaHPO4 that donate H+)
sometimes if start water with alkalinity and get pH adjusted, pH can bound back from 5.7 to 6.1 after spraying due to CO2 vaporization.....

====
Xavier's system is strange....
If you get ~pH6, in equilibrium with CaCO3(s), then its unlikely to get a low Ca2+(aq)or pH6 @Ca40ppm, unlikely to be in equilibrum with CaCO3(s); & as I remember CaCO3 @pH8.3 give you something like Ca20ppm...usually the solubility increase several fold per unit pH