Hello
I don't think eggshells in the nutrient solution will help with calcium because the calcium in eggshells is immoble. I'm pretty sure that you would have to decompose the shells and then they would be useful but in hydroponics that isn't very advisable. Could you let me know what kind of system you are useing and also what kind of fertilizer. Also if you could tell me the chemical analysis which is usually listed on the package. If you have Miraclegro or some other common fertilizer you should know that they are not complete fertilizers they are made for use in soil which already has many minor and micro nutrients. If you have any questions don't hesitate to ask me. I love growing hydroponic veggies and I think more people should give it a try.
Thanks
Amar Patel

Found this:
The main ingredient in eggshells is calcium carbonate (the same brittle white stuff that chalk, limestone, cave stalactites, sea shells, coral, and pearls are made of). The shell itself is about 95% CaCO3 (which is also the main ingredient in sea shells). The remaining 5% includes calcium phosphate and magnesium carbonate and soluble and insoluble proteins.
source:http://antoine.frostburg.edu/chem/senese/101/consumer/faq/eggshell-composition.shtml
i have not but eggshell is mostly calcium carbonate same as lime the lime is already finely powdered and would disolve easier. it would take a lot of eggshell to = a dollars worth of lime but i don't know how available or expensive lime is in hawaii. gypsum and calcium chloride would be other possible calcium sources but water soluble calcium nitrate is probably the best if you can find it. It is a good thought lets see urine wood ash eggshell we are getting close to a waste stream organic hydroponic solution, probably still need a waste stream acid to acidify things a bit more preferably a nitric. Could have potential for missionary type work feeding the starving of the world.

Could not find a local source of Calcium Nitrate which would have been great. I was boiling an egg at the time I was pondering how I could get some Ca into my hydro solution so I decided to ask the group about egg shells as a possible Ca source. But it looks like CaCO3 does not go into solution very well. Oh well.

My annual water quality report has a listing of hardness (ppm as CaC03) as well as calcium ppm. You might try calling them to clarify.

The links below have some discussion of calcium carbonate & eggs. Other calcium carbonate sources discussed include TUMS & pharmaceutical calcium carbonate. Some of these have inert ingredients, however. Powdered limestone also contains calcium carbonate. The problem with calcium carbonate is solubility, which may clog your pumps.

If you use egg shells you might want to make sure the inner lining is removed since it may degrade further. A heating method & acid method is suggested. Some of the acids in the acid method may result in products harmful to your system. I have not tried these personally so you might want to experiment with a pot system  using a plant you could afford to lose if the experiment failed.

Calcium carbonate & aquaponics (#10)
http://www.dec.ctu.edu.vn/cdrom/cd6/projects/krib_aquaria/caco3.html

calcium carbonate extraction
http://www.seps.org/oracle/oracle.archive/Expert/forbesm/Physical_Science.Chemistry/2002.05/001020648521.2701

Thanks Baci your expertise is always appreciated. I notice in your FAQ you mentioned CaCO3 could function as a pH buffer. Does this mean CaCO3 (eggshells, lime, etc.) helps reduce pH fluctuations? I notice somethimes I can vary a full pH point on a day to day basis.

If you have gypsum in hawaii it should be a little more soluble than the calcium carbonate it is calcium sulfate so would add a bit of sulfer it is often stated to be ph neutral but does have a slight acidifying effect. Doubt calcium chloride would be real common since we use it here as snow melt. the tomato blossom end rot preventer is calcium chloride solution here. We have gypsum quite cheap here but i have not tried to disolve it so it may be almost as dificult as ag lime.

I was wrong in saying lime is calcium carbonate although it is made from calcium carbonate. The lime used for to correct pH is probably hydrated lime, calcium hydroxide, which is a base. I donÂt think the calcium carbonate in the eggs will act as a buffer because it is stays in the shell unless it is altered. What is your pH doing, & what acid are you using?

Over time my pH rises. Usually as it hit 6.7 - 6.9 I add more nutrients till the pH drops to 6.1 - 6.3. The EC also rises to 1700 - 1900. After two weeks I replace the solution. I still need to add Calcium Ca+ though. How about CaSO4-2(H2O), as Markapp suggest? Not sure about availability of gypsum here. I can always scrap some off my drywall. haha!

I like MarkappÂs suggestion. Sometimes growers have problems with getting Ca into the nutrient because they are in areas where they can not get calcium nitrate. They may have to substitute materials that are less soluble because that is what is available.

EC is a measure of the total ion content of the nutrient. When you are working with acids & bases you are dealing with ions so they interrelate.

The upward drift in pH is probably due to plant roots absorbing anions, especially nitrate. Some growers add ammonium (about 10-15% of the total nitrogen) to compensate for this. Adding too much ammonia can hurt the plants.

Some threads on this are:

Ph levels ect
http://forums.gardenweb.com/forums/load/hydro/msg050510018323.html

Help with pH please!
http://forums.gardenweb.com/forums/load/hydro/msg0718461324859.html

pH up or pH down using commonly found household chemical
http://forums.gardenweb.com/forums/load/hydro/msg060920042111.html

ground lime or ag lime should be calcium carbonate, same as powdered eggshell basicly. the calcium hydroxide is usually labelled as slaked lime or builders lime. dolomite is yet another variation used for soil amendment. The calcium hydroxide is often labeled as such the ground lime here is often not labeled with a chemical name. hydroxide is generally not sold as ag/garden use here. midwest mainland USA.

Amonia will raise the ph it is a strong base you will need acid to lower it the cheapest easiest to find is probably muratic as long as you can tolerate the chlorine. Amonium nitrate would be acidic but it is almost obsolete now, so it may not be available. Nobody around here sells it.

I think the idea was to limit the ammonia to about 10% of the total nitrogen  just enough to prevent the upward pH drift.

It looks like type of lime one can get depends on the area one lives in. I am unable to get aglime, but can get hydrated lime. The Dolomite lime is a calcium & magnesium material, hydrated lime is calcium hydroxide, & as you said markapp ag aglime is calcium carbonate. It would make a difference in terms of nutrient interactions & possible problems.

http://www.lime.org/faqs.html

There are different types of gypsum & the agricultural gypsum CaSO4-2(H2O) is what is available in my area. Solubility may be an issue since calcium sulfate can precipitate out of solution. I do not know what is in drywall - I would think an agricultural form would be better than drywall but you could always experiment. It might help to finely grind the particles.

trust me you don't want drywall. It has way too much other stuff. I am not even sure if it is safe to compost it into food production soils.

Well I'm just going to have to find some Ca(NO3)2·4H2O somewhere. Thanks guys.

Miracle grow has a tomato plant nutrient with calcium, but will only sell it in Australia. I called them and they said they only supply soil based products in US. I asked them futher if I could order from Australia and they stated that I could order, but they probaly would not ship it into US. The MG with calcium in Australia is all that is needed according to their write up.(below)

Miracle-Gro® Water Soluble Tomato Plant Food
This fertiliser is especially suitable for growing tomatoes and all vegetables.
High in nutrients
Miracle-Gro® Water Soluble Tomato Plant Food is formulated to promote crops of hearty, healthy vegetables. The NPK is 20:2.2:9. This product is unique among water-soluble fertilisers because it contains high levels of calcium which are essential for preventing blossom end rot in tomatoes and help all vegetables to resist diseases. The product also contains iron, magnesium and essential trace elements such as copper, zinc, boron, manganese and molybdenum. The unique wetting agents help to maximise foliar feeding as well as to ensure that the fertiliser is readily absorbed into the soil to reach the roots quickly.
Hydroponics
Because of the revolutionary new technology used in this fertiliser, the added calcium does not settle out. This allows Miracle-Gro® Water Soluble Tomato Plant Food to be used in hydroponics alone, not as a mixture of an A & B solution.
Application rate
A measuring scoop with a large and a small end is provided. Dissolve 1 level large scoop in 4 litres of water and apply the product every 7 to 14 days to the leaves and to the soil surrounding the plants. When planting tomatoes use approximately 1 cupful (250ml) of the solution for each plant. Increase the amount as the tomato plants grow until you are applying 4 litres per plant per feeding.

Here is a link that might be useful: /miracle-gro.htm

Hi Hank Mili,

Using eggshells as a source of Calcium for hydroponics is not a good idea because eggshells are basically Calcium Carbonate which will react with Phosphorus in your nutrient solution and precipitate out as insoluble Calcium Phosphate, which is not freely available to your plants.

Eggshells, limestone, garden lime, sea shells, marble and the White Cliffs of Dover (in the UK) are all composed basically of Calcium Carbonate.

Blackboard chalk, gypsum and Plaster of Paris are all basically Calcium Sulphate, which would not be a good source of Calcium because all are practically insoluble in water.

Dolomite, a Magnesitic limestone would not be a good source of Calcium because of its relative insolubility.

A good nutrient solution needs between 100 and 400 mg/L of soluble Calcium, and the best source is from Calcium Nitrate, which supplies both Calcium and Nitrogen.

Calcium Nitrate is hygroscopic and sells for about A$20.80 per 25 kg bag in Australia. You should be able to import some to Hawaii from China, South Korea, Japan or the mainland US for very much the same price.

In regular hydroponic nutrients, the pH does rise on a daily basis as the nutrient is consumed by the plants. The pH is best reduced by using dilute Sulphuric Acid.

Cheers,
Jimr007.

I took organic shells dried them in the oven at 175 degrees and put them in my powerful blender. They made a wonderful,fine powder. I am now wondering if I would rather put them in a smoothie or spread it on my garden! Jan2007

I didn't see it mentioned but, honestly, the further along I read, the more I browsed. Epsom salts are a good source of soluble calcium you can add to your hydroponic solution.
available at just about every drug store there is.

Uhh . . grizzman,

Epsom salt is magnesium sulfate.{{gwi:1002854}}

Hello there! I hope I´m not too late.
Plants can only absorb soluble calcium, and the eggshells are Calcium Carbonate that is very insoluble. So it´s better to buy some cheap Calcium Carbonate than using eggshells. But you have to disolve Calcium Carbonate. Wait!! there´s a little secret.
Easy! Just add to Calcium Carbonate some water and Citric Acid. Citric Acid complex calcium and eliminates carbonate (CO2), and it´s a very acid with buffer capacity. ;-)
How much you may ask? That´s your work!

Whitewinevinegar plus groung eggshells that hav been boiled and ovened releases the Ca+

10 % toasted eggshells in qt jar crush slightly, cover with raw acv, when it foams its ready, strain, it makes the calcium soluable, 1 Tbsp per 4 gallons foliar spray, refer to Nigel Palmer Regenerative Growers Guide

Interesting...haven't you compared the list on a vitamin bottle to that on a n-p-k plant food list. The same things are listed. You take a liter of urine and 2gal water and you have an organic plant food. One that doesn't rely on ph to force feed plants. And it can be foliar sprayed as well. That's old school, much older than these post that get dug up. Water is the main ingredient in hydroponics and it's becoming a high priced ingredient. Without it you couldn't have hydroponics. But the hydroponics of run to waste is over. All these mythologies of waste.

Is this a joke?? A litre of human urine??