Ph problems in nutritive solution stored in semi hidroponic pots

[Georg Luiz Barth]

Greetings to the members of this prestigious forum. I apologize for my English....I am Brazilian. Please, I have a question about pH variation in the nutrient solution stored in the pots of my semi hydroponic system and this exclusively in my cattleyas. No matter what the initial pH of my nutrient solution is...it invariably drops to 3.5 after a few hours. I've experimented adjusting the initial ph from 5.5 to 7.0...and the result is always the same. I use a version of the k-lite formula that I made myself based on the package information, because we don't have this product readily available in Brazil. I'm a chemist, so I don't have many difficulties in making the nutrient, but of course studying all the wonderful information on the First Rays website, which I highly prestige. I use the following raw materials to compose the formulation: calcium nitrate, magnesium nitrate, monoammonium phosphate, potassium nitrate, and a commercial formula of micro elements such as molybdenum, boron, zinc and chelated metals such as iron, manganese, copper and nickel. I'm currently testing the addition of a little magnesium sulfate, decreasing of course the magnesium nitrate. When using rainwater I need to increase the pH with potassium or calcium hydroxide. When I use water from the municipal supply, I need to lower the pH with phosphoric acid, remembering that tap water in the region where I live has a low TDS, around 30, so I'm thinking of eliminating rainwater, because of the work it takes. in collecting it. The interesting thing is that in phalaenopsis, the opposite occurs... the solution tends to become alkaline, but at a very slow pace, which in my point of view, does not generate any problem. Watering is done with 25 ppmN nutrient solution every two or three days, filling and emptying the pots, thus maintaining the solution level in the drain holes. Well folks, I fear that the roots of the cattleyas may be suffering from this pH of 3.5 or, in the worst case, some of the nutrients are not being absorbed by them. The bulbs are growing slowly without any apparent problems, but I haven't gotten flower stems yet. Please, any comments on this topic? Thanks in advance.

---------- Post added at 10:22 AM ---------- Previous post was at 10:09 AM ----------

Originally Posted by Georg Luiz Barth

Greetings to the members of this prestigious forum. I apologize for my English....I am Brazilian. Please, I have a question about pH variation in the nutrient solution stored in the pots of my semi hydroponic system and this exclusively in my cattleyas. No matter what the initial pH of my nutrient solution is...it invariably drops to 3.5 after a few hours. I've experimented adjusting the initial ph from 5.5 to 7.0...and the result is always the same. I use a version of the k-lite formula that I made myself based on the package information, because we don't have this product readily available in Brazil. I'm a chemist, so I don't have many difficulties in making the nutrient, but of course studying all the wonderful information on the First Rays website, which I highly prestige. I use the following raw materials to compose the formulation: calcium nitrate, magnesium nitrate, monoammonium phosphate, potassium nitrate, and a commercial formula of micro elements such as molybdenum, boron, zinc and chelated metals such as iron, manganese, copper and nickel. I'm currently testing the addition of a little magnesium sulfate, decreasing of course the magnesium nitrate. When using rainwater I need to increase the pH with potassium or calcium hydroxide. When I use water from the municipal supply, I need to lower the pH with phosphoric acid, remembering that tap water in the region where I live has a low TDS, around 30, so I'm thinking of eliminating rainwater, because of the work it takes. in collecting it. The interesting thing is that in phalaenopsis, the opposite occurs... the solution tends to become alkaline, but at a very slow pace, which in my point of view, does not generate any problem. Watering is done with 25 ppmN nutrient solution every two or three days, filling and emptying the pots, thus maintaining the solution level in the drain holes. Well folks, I fear that the roots of the cattleyas may be suffering from this pH of 3.5 or, in the worst case, some of the nutrients are not being absorbed by them. The bulbs are growing slowly without any apparent problems, but I haven't gotten flower stems yet. Please, any comments on this topic? Thanks in advance.

I wrote it in English, but I'm not sure if the message sent was automatically translated into Portuguese by my cell phone. If this happened I apologize. Can anyone tell me if this topic is actually written in English?

---------- Post added at 10:41 AM ---------- Previous post was at 10:22 AM ----------

I noticed that there is an exclusive forum for topics related to semi hydroponics. I ask the forum moderator to feel free to transfer this matter to the appropriate forum, if necessary. Sorry for the misunderstanding.

[Roberta]

First, Welcome!
It is, indeed, in excellent English.
I will leave it to other members to respond to your questions, since I do not use the semi-hydroponic approach myself.

[Shadeflower]

I have spent the last year discovering how important K is for my orchids so I cannot comment doing the opposite to promote what I do.

Potassium Nutrition Affects Phalaenopsis Growth and Flowering in: HortScience Volume 42 Issue 7 (2007)

When mixing nutrients you should let the bucket settle first as the PH can change in the first 12 hours. So you mix, let it stand, measure, adjust, then use it.

What you end up using is up to you. Less K because you heard it has some merit or more K because K is important for flowering.

I know what I'd do and there is less ph problem then too but we all have to decide what to believe in our lives

[Georg Luiz Barth]

Originally Posted by Shadeflower

I have spent the last year discovering how important K is for my orchids so I cannot comment doing the opposite to promote what I do.

Potassium Nutrition Affects Phalaenopsis Growth and Flowering in: HortScience Volume 42 Issue 7 (2007)

When mixing nutrients you should let the bucket settle first as the PH can change in the first 12 hours. So you mix, let it stand, measure, adjust, then use it.

What you end up using is up to you. Less K because you heard it has some merit or more K because K is important for flowering.

I know what I'd do and there is less ph problem then too but we all have to decide what to believe in our lives

I understand your statement about K. I believe that my level of knowledge on this subject is too low to give an opinion. Actually, I'm just trying to understand why only in cattleyas I have a problem of rapidly lowering the pH of the nutrient solution, while in phalaenopsis the variation is much slower and in the opposite direction, that is.... slightly increasing the pH. Anyway, thanks for your opinion.

---------- Post added at 03:36 PM ---------- Previous post was at 02:21 PM ----------

Originally Posted by Shadeflower

I have spent the last year discovering how important K is for my orchids so I cannot comment doing the opposite to promote what I do.

Potassium Nutrition Affects Phalaenopsis Growth and Flowering in: HortScience Volume 42 Issue 7 (2007)

When mixing nutrients you should let the bucket settle first as the PH can change in the first 12 hours. So you mix, let it stand, measure, adjust, then use it.

What you end up using is up to you. Less K because you heard it has some merit or more K because K is important for flowering.

I know what I'd do and there is less ph problem then too but we all have to decide what to believe in our lives

Interesting article about K deficiency...thanks

[Ray]

Georg - welcome to the forum.

Concerning the pH in the reservoir of a semi-hydroponic pot, my advice is to "ignore it".

Many years ago, several others and I did some testing and saw precisely the kind of variation you have seen. In over 25 years of growing plants in S/H culture, I have never seen an issue, despite the pH variation.

That "readjustment" happens because the plant is actively absorbing nutrient ions and secreting compensatory ones.

If you would like to experiment more, water thoroughly with your "pH adjusted" fertilizer solution, then test the pH periodically over the next 24 hours. The pH you measure at different times of the day is likely to vary as well.

As an aside, despite some studies and the repeated nonsense of some individuals, I have grown thousands of plants with a low-K & P formula over the last decade, and experienced none of the shortcomings professed. That suggests to me that there are other variables that may not have been considered.

[WaterWitchin]

I’ve only grown exclusively in SH for maybe 15 years. Before that, both SH and a bark medium. I didn’t even start fertilizing consistently until about ten years ago, and still sometimes sporadically. Frankly I grew out orchids about as well as I did 25 years ago. Orchids don’t need much in the way of nutrients, at least in my environment and culture.

pH…. Have never paid attention. As Ray indicates, isn’t really something to spend much time thinking about. Again, my opinion.

Do you do a flush on your semi-hydro at least once a week?

[Georg Luiz Barth]

Originally Posted by WaterWitchin

I’ve only grown exclusively in SH for maybe 15 years. Before that, both SH and a bark medium. I didn’t even start fertilizing consistently until about ten years ago, and still sometimes sporadically. Frankly I grew out orchids about as well as I did 25 years ago. Orchids don’t need much in the way of nutrients, at least in my environment and culture.

pH…. Have never paid attention. As Ray indicates, isn’t really something to spend much time thinking about. Again, my opinion.

Do you do a flush on your semi-hydro at least once a week?

Hello.... answering your question, yes I wash the pots by running tap water abundantly over the leca... but monthly. Since I use a well-diluted nutrient solution, I don't have any problems with salt formation.

---------- Post added at 08:59 PM ---------- Previous post was at 08:40 PM ----------

Originally Posted by Ray

Georg - welcome to the forum.

Concerning the pH in the reservoir of a semi-hydroponic pot, my advice is to "ignore it".

Many years ago, several others and I did some testing and saw precisely the kind of variation you have seen. In over 25 years of growing plants in S/H culture, I have never seen an issue, despite the pH variation.

That "readjustment" happens because the plant is actively absorbing nutrient ions and secreting compensatory ones.

If you would like to experiment more, water thoroughly with your "pH adjusted" fertilizer solution, then test the pH periodically over the next 24 hours. The pH you measure at different times of the day is likely to vary as well.

As an aside, despite some studies and the repeated nonsense of some individuals, I have grown thousands of plants with a low-K & P formula over the last decade, and experienced none of the shortcomings professed. That suggests to me that there are other variables that may not have been considered.

Thank you Ray for your observations. I'll try not to worry too much about this issue...but it won't be easy due to my technical nature. I will certainly do some experiments in the fertilizer formulation, trying to use raw materials that contribute to greater stability in the exchange of anions and cations between the roots and the nutrient solution. But I hope I don't want to invent the wheel again...heheheh

[estación seca]

Welcome to the Orchid Board!

I live in a very warm summer climate. You don't mention which part of Brasil.

Try completely flushing your pot with fresh solution at each watering. Ray discusses this - the more you water your plants in S/H, the better they grow. Once a month is not often enough. I have seen my plants grow much better when I flush them very often. I wish I had time to do this every day.

Ray has written he uses his dilute fertilizer solution at every watering, and he flushes completely at every watering. Sometimes I use plain water on my plants when I don't have time to mix more fertilizer solution. I suppose they might grow better but they still do grow.

[Georg Luiz Barth]

Originally Posted by estación seca

Welcome to the Orchid Board!

I live in a very warm summer climate. You don't mention which part of Brasil.

Try completely flushing your pot with fresh solution at each watering. Ray discusses this - the more you water your plants in S/H, the better they grow. Once a month is not often enough. I have seen my plants grow much better when I flush them very often. I wish I had time to do this every day.

Ray has written he uses his dilute fertilizer solution at every watering, and he flushes completely at every watering. Sometimes I use plain water on my plants when I don't have time to mix more fertilizer solution. I suppose they might grow better but they still do grow.

Yes...My watering is done with 25 ppmN nutrient solution every two or three days, filling and emptying the pots, flushing the Leca pebs with the solution ... then I keep the solution in the drain holes level. But once a month I wash/flush the pots by running tap water (TDS 30 ppm) abundantly over the leca, to eliminate salts and eventually decomposing organic matter. Ah... by the way, I live in the State of Santa Catarina, southern Brazil.

[estación seca]

Originally Posted by Georg Luiz Barth

Yes...My watering is done with 25 ppmN nutrient solution every two or three days, filling and emptying the pots, flushing the Leca pebs with the solution ... then I keep the solution in the drain holes level. But once a month I wash/flush the pots by running tap water (TDS 30 ppm) abundantly over the leca, to eliminate salts and eventually decomposing organic matter. Ah... by the way, I live in the State of Santa Catarina, southern Brazil.

OK, I misunderstood.