# Trying to understand crushed shell



## isu712 (Feb 8, 2008)

I want to set up a 2.5 gallon NPT and am trying to figure out the best way to do so. I tried searching the forum for about 15 minutes already and couldn't quite find the answer I was looking for. From what I gather here it seems like people add some form of crushed shell to increase the hardness of their water. If my water is pretty hard straight out of the tap can I just skip this step? I think that the GH is around 8, but the KH is around 2 or so. I know that the shell would add CaCO3 to the tank which would raise the KH, so would I want to do this? Any feedback would be helpful


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## dansbdk (Mar 16, 2008)

good question!, i'd like to know the answer also, 
& is dolomite lime a good substitute?


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## isu712 (Feb 8, 2008)

I'm glad someone else out there is in the same boat. Now...if we can only get someone to respond.


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## trackhazard (Sep 20, 2006)

NPT usually require a minimum of water changes. As the plants grow, the hardness of the water changes as minerals are utilized. Without regular water changes to replenish the carbonate in the water and the addition of decaying plant matter to further reduce hardness, the initial gh/kh levels will not remain constant, hence the addition of some sort of hardness booster.

At least that is how I understand it.

-Charlie


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## dansbdk (Mar 16, 2008)

Oh yes!, ok!, very logical! 
The concept is now very clear!

But, still the question is.... 
(in practice
To use crushed shells? or dolomite lime pellets? 
And how much do you actually use to keep KH/GH from going off the charts, and becoming toxic? 
is there a chart, or method to help calculate how much to apply?

I read in the "setting up an El Natural tank" link that "some" crushed oyster shell is used", and else where, "dolomite pelleted lime can be used instead of crushed oyster shell" but, what's "some"? 
a 10 pound bag full?, a thumble full?, milligrams?
is it a seperate layer? or mixed into the soil?
Would I use the same amount in a 10 gallon, as I would a 55 gallon?

AAAaaaarrrrgggghhhh! 
"Calgone take me away!"


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## isu712 (Feb 8, 2008)

Thanks trackhazard, that answers my question. It would still be nice to know how much as well.


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## newbie314 (Mar 2, 2007)

I use crushed eggshells.
1/8 teaspoon per day. 
I also just have a half eggshell for hiding spots.
I've stopped now that the GH and KH is high enough. I'll be interested what is looks like in the future, since plants will use the minerals, but the egg shell may still be disolving (delayed response, old eggshell may still be entering the water column)


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## rohape (Feb 7, 2005)

My understanding is that hardness is not a bad thing. I don't really know of any plants that have a target hardness level other than just being hard or softwater plants. I eyeballed it, and when my GH started dropping added some more shell until I found that "zone" where it was staying steady. One thing I did notice is the crushed shell did not keep my KH high enough and started causing problems. My KH is now at 0, and my Ph has dropped. I'm hoping to fix this with Calcium Carbonate....calcium sand. We'll see how this goes, I just added some yesterday. 
So I guess what I'm saying and my thoughts are that it's hard to target a specific harness level due to all the variables (variety of plants use different metals at a different rate, fish...same thing). Maybe a hand full of shell for your 2.5.


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## isu712 (Feb 8, 2008)

Thanks for the info. Now I'll just have to find some.


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## ItsDubC (Jan 12, 2008)

I just recently set up a 10gal NPT and was wondering the same thing. In trying to find more info about quantities to add etc, I came across a thread on another site in which one of the posters noted that his crypts grew much better in soil containing crushed eggshells than soil without. I was already set on using crushed eggshells in my soil underlayer because other ppl, such as n314, have had success w/ it and I didn't want to buy a whole bag of crushed oyster shell just to use a fraction of it in my 10gal.

I eventually gave up trying to find an exact amount of eggshells to use in the soil underlayer, and just tried to estimate the volume of the crushed oyster shell used in DataGuru's guide to setting up an NPT that's a sticky in this forum, and scale it to a 10gal. The next day, I made myself an omelette out of 3 eggs, saved/washed the eggshells, and left them out in the sun to dry. I then crushed them as fine as I could and added them to the soil in my 10gal that I had been airing out for a few days to degas excess ammonia.

I set up the NPT the next day and it's been a week so far. My plants are doing great, though for this NPT I'm trying not to be too concerned w/ testing water parameters so I don't know what the GH/KH are. All I know is that so far, so good.


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## isu712 (Feb 8, 2008)

Sounds good. I think I'll have eggs for breakfast tomorrow then.


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## dwalstad (Apr 14, 2006)

isu712 said:


> I want to set up a 2.5 gallon NPT and am trying to figure out the best way to do so. I tried searching the forum for about 15 minutes already and couldn't quite find the answer I was looking for. From what I gather here it seems like people add some form of crushed shell to increase the hardness of their water. If my water is pretty hard straight out of the tap can I just skip this step? I think that the GH is around 8, but the KH is around 2 or so. I know that the shell would add CaCO3 to the tank which would raise the KH, so would I want to do this? Any feedback would be helpful


If your GH is 8, you really don't need to add shells. I only advised increasing water hardness when the tapwater is very soft (GH 0-4) [my book, page 185]. That was to insure that plants got the calcium and magnesium they need.

If your KH is truly 2 or less, this means there's not much bicarbonates for plants to use as a carbon source. You could add a small amount of baking soda (a pinch or 1/8 teaspoon). That should be plenty for a 2.5 gal tank. Baking soda is pure sodium bicarbonate and should immediately bring your KH up (it will also bring pH up, so don't overdo it). Egg shells, oyster grit, and dolomite lime take a much longer time (weeks, months) to dissolve.

In the end, I suspect that your water is probably fine for setting up your tank. Plus, many soils will release calcium, magnesium, and bicarbonates into the water (see my book, Fig VIII-6 on p. 131). Thus, readings of your aquarium water may end up much different than your tapwater.

Remember that aquariums are complicated ecosystems. Sometimes you just have to set up your tank as best you can and wait. Again, I recommend starting with a large variety of plant species. Invariably, there will be a few species that will adapt to the conditions you provide. Thus, you don't have to have "spot-on" perfect water chemistry. Let the plants do the work!


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## isu712 (Feb 8, 2008)

I'm definitely more than happy to let the plants do the work for me. I checked the KH of my tap water last night because I hadn't done it in a while (2 was what I thought I remembered from the last time I did it). Turns out I have a KH of 4. I think I'll just go ahead and set it up without adding anything except for a small pinch of baking soda to get that initial KH up. I don't mind testing periodically for a while (I also have a high-tech planted tank so I'm used to it). I'll keep an eye on the water parameters and hope for the best.


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## dansbdk (Mar 16, 2008)

i've found that "TUMS for heartburn" are Calcium Carbonate! I've been dropping 1/8th of a tablet in my 10 gallon along with 1/8 tsp of baking soda daily to keep the PH at about 6.8 and KH at about 7.5. it's been keeping things steady so far. I've got a mini co2 reactor in there too.
My plants are growing like mad!


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## newbie314 (Mar 2, 2007)

Tums only CaCO3.
I thought there would be other additives that might be harmful.


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## rohape (Feb 7, 2005)

dansbdk said:


> i've found that "TUMS for heartburn" are Calcium Carbonate! I've been dropping 1/8th of a tablet in my 10 gallon along with 1/8 tsp of baking soda daily to keep the PH at about 6.8 and KH at about 7.5. it's been keeping things steady so far. I've got a mini co2 reactor in there too.
> My plants are growing like mad!


Snails love them too!!!!!


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