well water ph, filtering. fertilizers

[Ray]

Originally Posted by Brian1212

i suppose the citric acid would be my last resort although I would never use it because it would degrade

What would make you think it degrades?

Citric acid has three acidic hydrogens that can hydrolyze, and the driving force for the third is so low, that it doesn't really happen, keeping the molecule intact in solution.

Such organic acids - citric and malic, specifically - are integral to plant physiology, so I'd think using them would be my first choice.

MSU WW, MSURO, and K-Lite contain citric acid, as it's the preferred solubility aid.

[Brian1212]

hi ray,
citric acid is the juice of a lemon. What makes me think it degrades is that all organic matter degrades and rots. Apple juice, orange juice, kiwi juice. They will all develop a layer of mould if left out for a few days and turn sour.

You might be right that the acidity of lemon juice protects it from such decay but not forever. Lemon juice will too develop mould and degrade.

I won't be risking it and there never has been a need unless there wasn't a good cheap product readily available in every shop in every city in the world.

---------- Post added at 08:50 AM ---------- Previous post was at 08:40 AM ----------

Originally Posted by camille1585

About a year ago I started using a pure water formula of MSU type fertiliser with my tap water, after the maker/vendor of it told me my water was soft enough and low enough in TDS to use it and didn't seem concerned about the pH (8). A year on, my impression is that my plants are not doing as well as they did with my previous fertiliser. So I bought an aquarium water pH test kit since it's affordable and relatively accurate. Tapwater is at 8 as my water report indicates, and 7.5 with fertiliser. I could get it down to 6-6,5 by adding only 0,7ml/L of vinegar.

I'm still wondering if this is the best decision, and if it isn't better to go back to my old 20-20-20 fertilizer. But seeing how much of the MSU stuff I have left, it seems so wasteful to throw it out.

Hi camille, I'm afraid I don't know what MSU stuff is. I haven't really had any bad experience with any fertilizer - just the way I have used it.

From your post it sounds like a high ph was the problem for you and these things take months to correct. Changing fertilizer or anything else for that matter might do good but you will never know for sure in the end because you have ended up changing too many different variables. If you did have good results with the old fertilizer maybe go back to it - then try half with one fert and half with the other and compare results in a couple months to see which one you prefer althugh even a couple of months might be too little to see any real differences.

[camille1585]

Originally Posted by Brian1212

hi ray,
citric acid is the juice of a lemon. What makes me think it degrades is that all organic matter degrades and rots. Apple juice, orange juice, kiwi juice. They will all develop a layer of mould if left out for a few days and turn sour.

You might be right that the acidity of lemon juice protects it from such decay but not forever. Lemon juice will too develop mould and degrade.

I won't be risking it and there never has been a need unless there wasn't a good cheap product readily available in every shop in every city in the world.

Citric acid is found in lemon juice, but if you buy pure citric acid in crystal form, then you have no issues with contamination/degradation. The pure form is preferable since once you've made your initial calculations to determine the amount to add to your water to reach your target pH, you know that you are always adding the same thing. And it doesn't spoil!

Originally Posted by Brian1212

Hi camille, I'm afraid I don't know what MSU stuff is. I haven't really had any bad experience with any fertilizer - just the way I have used it.

From your post it sounds like a high ph was the problem for you and these things take months to correct. Changing fertilizer or anything else for that matter might do good but you will never know for sure in the end because you have ended up changing too many different variables. If you did have good results with the old fertilizer maybe go back to it - then try half with one fert and half with the other and compare results in a couple months to see which one you prefer althugh even a couple of months might be too little to see any real differences.

MSU fertiliser is a formula developed by the university of the same name in the US, and is widely used by growers since it often gives excellent results (assuming all other culture requirements are met). In Europe Akerne Orchids sells a version of it, sold as Akerne Rainmix. You are right that it takes a while to see the effects of fertilizer, which is why I decided to use it for a year (so entire growth and bloom cycle) before evaluating how my plants were performing. What I noticed was less vigorous growth and lower flower count on spikes.

[thefish1337]

I used citric acid to pH a hydroponics flood and drain reservoir for growing peppers and tomato seedlings. Citric acid only held the pH low for about 24 hours before being converted by "something" (i have heard that it can be used as a carbon source by some bacteria) the pH then swung up rapidly to over 7.8. Totally unsustainable so I ended up buying some pH down by GH. Ph down contains phosphoric acid, citric acid and ammonium phosphate. Way easier, and much more stable for controlling pH, the inevitable pH swing up still occurred but it was much slower and easier to manage in comparison to just citric acid. Personally i wouldn't recommend relying on organic acids to pH your nutrients - they only give you a superficial lowering of pH before degrading. If you water in with organic acids, the pH rise will occur in your media and you may end up with more precipitation of salts as opposed to keeping your media more acidic with better pH buffering. Just my $0.02 some people say pH doesn't matter that much, I think it does.

[Ray]

pH is important, but one must ask “what pH?” and consider the circumstances surrounding it.

The pH within the rhizosphere is quite important, but that doesn’t mean that the pH of the applied solutions are.

In soils, where pH affects the Cation Exchange Capacity (CEC), it can greatly affect what nutrient ions are available and which aren’t. Orchid media have extremely low CECs compared to soils, so that effect can be disregarded.

Plus (and this is something I had not considered until a Professor at NCSU mentioned it to me), a shift in pH does not mean that every ion is affected. With hydroponic systems (and that’s really what orchid growing is, as the medium is primarily for mechanical stability, and water and nutrient storage, rather than being a source of nutrition) the amount of nutrient applied is far greater than it can use, so “plucking” the necessary ions is not difficult for the plants.

I have also read that organic acids can contribute carbon directly to the plants, supplementing what they get from the air, giving them a growth boost.

[thefish1337]

Ray, I agree with you that growing orchids is like hydroponic culture. The vast majority of plants in water culture are grown at acidic pH between 5.5-6.5. As an orchid grower I'm trying to provide the best conditions for my plants not just conditions they "tolerate". I'd also hazard a guess that most epiphytic orchids prefer that range as well given the pH of rainwater. Organic acids by themselves are just not suitable for stable pH control in a hydroponic system. I know, I've tried it and wasted a lot of time trying to manage pH when I should have just bought "pH down" or made a weak nitric, sulfuric or phosphoric acid solution.