Calcium & magnesium supplementation

[Brabantia]

Hi All,

Just a thought about a previous comment I made. I use the Dyna Gro bloom to decrease the PH from the Akerne PH of around 6.4, (at the recommended strength of around 650 u/S).to 5.9.

Strange that you measure a pH of 6.4 with Akerne RM in RO water. This fertiliser is prepared with salts of weak base and strong acid . What is the conductivity of your RO water?
I never found a mineral fertiliser which is giving a so high pH in RO water. Have you checked your pH meter? Using very pure salts I have prepared many fertilysers formulas and always they are giving a pH around 5.6 in pure water (DI water, RO water or rain water). Same thing with AKERNE RM. It is the salts contained in the fertiliser which impose the pH of the solution because all the "pure" water have no buffer capacity.

 

[Carper]

Strange that you measure a pH of 6.4 with Akerne RM in RO water. This fertiliser is prepared with salts of weak base and strong acid . What is the conductivity of your RO water?
I never found a mineral fertiliser which is giving a so high pH in RO water. Have you checked your pH meter? Using very pure salts I have prepared many fertilysers formulas and always they are giving a pH around 5.6 in pure water (DI water, RO water or rain water). Same thing with AKERNE RM. It is the salts contained in the fertiliser which impose the pH of the solution because all the "pure" water have no buffer capacity.

I have always used RO water and it has always read around the 7.0 ph mark. I often change the filters/units etc. I have only just replaced my PH meter and recalibrated it. I have been using the Akerne now for a good few years and the pH has always been in the range of 6.2-6.4. I can only comment on what I have been doing since first using the Akerne and the new adjustments down to the 5.9 range have been positive.

Gary

 

[Ray]

Gary.

Collect a glass of your RO water, and let it stand out overnight. If you still have a pH of 7.0 the next day, either it's not very pure, so your RO system needs work, or your meter does.

The equilibrium pH of the solution of pure water with the CO2 in the air is about 5.4.

 

[naoki]

Can your ph meter really measure ph of ro water? My typical (lab grade) probe doesn't stabilize. I think ChrisFL explained this in another thread.

 

[cnycharles]

I think cheaper meters would be less moveable in response, and likely show a particular reading like ray is suggesting? I think I got similar readings with my portable meter when I first set up my r/o unit

 

[Carper]

Gary.

Collect a glass of your RO water, and let it stand out overnight. If you still have a pH of 7.0 the next day, either it's not very pure, so your RO system needs work, or your meter does.

The equilibrium pH of the solution of pure water with the CO2 in the air is about 5.4.

Ray,

I run off my RO water and let it acclimatise to the temp in the greenhouse for a few days before using it. I measure the temp, Ph and the dissolves solids before and when making up my solution. For about 7 years now I have been carrying out the same routine and the readings have all roughly come out as being PH 7, approx. reading of 4 to 20 u/S and my temp is about 16C. What I have running also are airstones in the water. Even when I purchased a new pen or changed the filters etc the readings have been very close to these. As I have been getting good growth generally over the years and even recently amending the PH down to 5.9, and feeding on what I think is correct, what have I been giving them ?? I have just tested the RO I ran off 3 days ago and it has a reading of 13 u/S and a pH of 7.0!

My RO unit looks fine at present so a bit unsure where to go next with this.

Gary

 

[Ray]

That would come in somewhere between 5- and 10 ppm solids, so that's OK for a residential system.

Makes me question the meter.

 

[Carper]

That would come in somewhere between 5- and 10 ppm solids, so that's OK for a residential system.

Makes me question the meter.

I've used brand new hanna meters and the cheap ones but replace them regularly. All of them have only required a very slight adjustment if any when I used them for the first time. I calibrated them in the usual ph 4 & 7 solutions and the readings given were as I've mentioned previously. My present meter is only a few weeks and seems to be performing Ok.

Gary

 

[gego]

There is a solution recommended to use after using the meter like for storing. Basically you want to start from the same ref every time you use the meter. If you just wash the probe with tap water after using the initial reading will be initially towards the tap water. The RO or rain water may not be able to move that reading. I was advised not use tap and never let the probe go dry with the solution you last measured.

For storage it's best to soak the probe to a certain pH like 4. Then if you want to measure rain or RO, soak that probe first to a ref 7 pH then rinse with RO or rain from a separate container and then measure your RO/rain.

Never let the probe dry up from solutions that have high TDS, salt will build up.
Hope this helps.

 

[SlipperMatt]

I made a little research in the near past, and I would share some info about it. The following datas had been found on Yara's website.
Firstly: Yaraliva Calcinit (calcium nitrate) 15,5N-0P-0K-26CaO Mono fertilizer sufficient dose is 0,05-0,15% solution in horticulture, and possible to use as leaf or normal watering fertilizer also. For orchids i belive, that 0,05% solution is enough, what means in ISO standard: 0,5gr salt /1 liter irrigation water. It means 77ppm N + 95ppm Ca @ every single watering. It should use in vegetative (growing) peroid. It mustn't mix with magnesium sulfate in one stock solution to avoid precipitations.
On the other hand: Yara Krista MgS (magnesium sulfate, epsom salt) 0N-0P-0K-16MgO-32SO3 Mono fertilizer sufficient dose is 0,05-0,1% solution. At 0,05% solution it means: 48ppm Mg + 65ppm S. The preferable watering technique is as leaf fertilizer. It mustn't use in flowering peroid to prevent the flowers against burns. Avoid to spray the leaves at strong daylight or at high temperatures (above 30C degrees).
Suggested methode to alternate the calcium nitrate with magnesium sulfate at every fourth watering cycle, what means 3-4 occasion of both in one growing peroid.

What do you think about this suggestions above for paphiopedilums?
The informations based not my experiences, but i will try it certainly.
I use balanced 20-20-20 NPK + micronutrients fertilizer at half strengt when i fertilize my plants in growing peroid from march to oktober dissolved in 1/3part chilled tap + 2/3 part RO water at pH 5,9-6 in bark mix . Every fourt watering is pour RO. Next i will sprinkle the leaves at every third occasion with calcium-nitrate, and every fourth occasion with epsom salt in dose as above. I would prevent my plants from suffering of Mg and Ca deficiency.
What is your experience/suggestion?

Kind regards:
Matyas

 

[troy]

Leaves can't absorb calcium

 

[gonewild]

Leaves can't absorb calcium

Yes the can.

 

[SlipperMatt]

Leaves can't absorb calcium

Than calcium nitrate supplying with normal watering through the roots as standalone fertilizer once a month, and epsom salt through the leaves will works? And whatabout with quantities and frequency? It looks sufficient?
Matyas