Backyard Aquaponics
A place to discuss aquaponics

I find that the shells if left to sit (not stacked together cause then they stick and the insides don't dry) for several days they can then be ground to powder in a coffee grinder for the worms. I figure for the AP system I don't really want the powder but if I take the dry egg shell and place it on the cutting board, just about anything with smash it flat into small bits that could go in a mesh bag to put in the system easily. I suppose if I put them out in the sun they would dry even faster.

I have, at times, had discussions with water filter manufacturers about treating the bore water I have at my place [lotsa Fe, Mg & some Na].
They recommended (as a first stage) using a header tank with the borewater sprayed in a fine mist (which makes the Fe drop out of solution when it picks up an extra O atom).
Regarding this discussion, they also recommended putting a leaky bucket (or one with holes in it) suspended in the water filled with chicken grits to buffer the pH.
Maybe if an AP pump had excess flow capacity it could be directed onto said bucket (I'm assuming that the return from the growbeds would have too much sludge to run directly onto a body of shell grits).
Apologies if similar stuff has been posted before - meesa newbie.

I have noticed several people writing about drying eggshells and pounding them before putting them in the tank. Why does it matter whether they are dry or not?

Also, can one 'overdose' on eggshells? My assumption is that they stop dissolving is calcium carbonate is not needed.

Thanks

You assume correctly.

The drying of them is mainly to make them easy to crush or pulverize. It they are not dry, that skin they have on the inside tends to resist being broken up and the bits/dust all sticks together kinda defeating the purpose of breaking them up. The purpose of grinding, pulverizing, or busting up the shells is to create more surface area so they can do the buffering quicker. I suppose if you have a huge amount of egg shell and not such an immediate need for the buffering, then they don't need to be broken up so much.

Just a side note concerning my use of washed shell as grow bed media. It does seem to be working and my pH has gotten quite stable at 7.6 (unless I need to add huge amounts of bore water to top up in which case the pH will be up higher for a little while.)

I have noticed that my plants seem to suffer more from Iron and maybe potassium deficiency at the higher pH and I need to add it more often that I thought would be normal.

Yep... See the chart TCL....

Ph lockouts are the worst thing as adding a load of what is apparently lacking.. won`t make a blind bit of difference and could cause you even more problems.
An over abundance of some elements cause lockouts too.
Too much potassium is probably the worse one as it affects calcium, magnesium, manganese, zinc and iron uptake.

I guess when plants start to look iffy, check the ph first then try to decide if its an excess or a deficiency

Ok .... just to make sure I understand this.

Crushed egg shell is place directly into the fish tank to dissolve?

Yep, pretty much.... Though we use shell grit and generally put it into an onion bag in the fish tank.

Oh ok .... yes I can see the sense in that. Cheers!

im planing on using oyster shells in the bottom of my sand fill/bioball fillter
ill let you know how it goes??
fingers crossed
and good luck to you

Oyster shells have been used before... work OK... but may need cleaning....

Don't use sand.... you will definitely need to remove/clean it constantly...

When it's said that these stabilize PH, does that also mean it will help it go down? - I get that the egg shells dissolve when the ph gets to low to help it stay up but what about the opposite - ph out of my tap is 8+ and staying the same in my system for weeks

No ... a carbonate buffer will always hold pH higher...

Your source water is undoubtably naturally carbonate buffered.... the nitrification process is acidic by nature and will drop pH over time....

If your grow bed media contains limestone, then it will hold pH high regardless of any thing you try to do...

You can adjust pH down by using Hydrochloric acid... but if your source water is buffered it will just bounce back until the carbonate buffer is all used up....

If you're going to treat your pH with acid... then treat the top up water, not the main tank... and be patient... it will take some time...