I've heard adding crushed seashells can be used to maintain calcium levels. Does anyone use this or know more about adding seashells as a Ca supplement? I've done a little bit of searching but haven't come across much other than different types of substrate.
Crushed Seashells Pros/Cons
- Thread starter thunderdood
- Start date
- Tagged users None
its commonly used in fw setups but in marine tanks I think the dissolution rate is too slow for coral uptake benefit, due to the ph we run. if any shells dissolved in my reef id be mad, its supposed to keep them! But then again fine grain sand has a way of slowly dissolving even at our ph, I just think its too slow of a process for the load the corals present to the system. can't wait to hear Randy's input
they do that lots of times in softwater tanks so snail shells wont fade away and im not even sure it works there, but its an anecdote ive seen in freshwater circles for years.
they do that lots of times in softwater tanks so snail shells wont fade away and im not even sure it works there, but its an anecdote ive seen in freshwater circles for years.
Randy Holmes-Farley
Reef Chemist
Staff member
Super Moderator
Excellence Award
Expert Contributor
Article Contributor
R2R Research
My Tank Thread
They cannot. Calcium carbonate will not dissolve in seawater unless the pH is very low.
Deep down in a sand bed where the pH may be low due to detritus degradation, some may dissolve, but not generally enough to be significant in a reef tank.
Randy is there any benefit to doing it in 7.0 co2 injected planted tank systems for the benefit of snail shells? they'll darn sure dissolve there (my tank will dissolve a whole shell in a month easy) but who knows if that becomes viable dietary calcium for the snail? I don't think it could benefit them any other way than internally/dietary I cannot fathom a mechanism other than feed intake for a snails shell to uptake calcium and not dissolve. my snails have shell issues anyway, so I either need more to dissolve (starts to undo my goal of softwater eventually) or I need to be feeding the snails better calcium supplementation am guessing
Randy Holmes-Farley
Reef Chemist
Staff member
Super Moderator
Excellence Award
Expert Contributor
Article Contributor
R2R Research
My Tank Thread
Calcium carbonate is supersaturated in the ocean, so won't dissolve unless the pH drops into the mid 7's or below. People use calcium carbonate in CO2 reactors all the time in reefs. Getting the pH down allows it to dissolve by reducing the concentration of carbonate.
As a supplement for calcium it has the attribute that it adds alkalinity in fixed proportions, so isn't suited to a substantial calcium jump in calcium as alk will skyrocket.
Belgian Anthias
Valuable Member
When a nitrifying biofilm grows on crushed shell and or aragonite the biofilm activities will have little effect on the pH and total alkalinity.
The pH measured in the water column will be different from the pH measured within the microbial community of a biofilm and the acids produced locally may dissolve the carbon carbonate on which the film grows. Also at system pH of 8.2 .
Crushed shells (oyster shell) can be used in a marine aquarium system, in biofilters and bioreactors. Using crushed shell in stead of sand as a substrate for a growing biofilm in an aquarium, in a biofilter or reactor, will prevent alkalinity may be depleted by autotrophic nitrifying and de-nitrifying processes taking place in a biofilter and or the aquarium. Some calcium will be produced . Crushed shell is used in marine aquaria for many decades, aragonite was not always common available. Crushed shells are part of the so called " Bio", used in Europe since the sixties, to stabilise pH and alkalinity, as advised by F.de Graaf. ( ref: FDeGraaf1969 >
Frank De Graaf. Handboek voor het tropisch zeeaquarium. Tweede druk. A.J.G. Strengholt N.V. Amsterdam, 1969. Graaf, Frank de. Marine Aquarium Guide. Harrison, N.J.: Pet Library, 1973. ) In the beginning crushed shells where used in the second compartment after the sand compartment. As nitrification mainly took place in the sand this did not work very good, mainly because the shell grit became bio-fouled. (SSpotte1970 >
Spotte, Stephen. Fish and invertebrate culture; water management in closed systems. New York: Wiley-Interscience, 1970. ) Replacing the sand in the first compartment of the "bio" by crushed shell solved the "biofilter syndrome" in a marine aquarium.
The pH measured in the water column will be different from the pH measured within the microbial community of a biofilm and the acids produced locally may dissolve the carbon carbonate on which the film grows. Also at system pH of 8.2 .
Crushed shells (oyster shell) can be used in a marine aquarium system, in biofilters and bioreactors. Using crushed shell in stead of sand as a substrate for a growing biofilm in an aquarium, in a biofilter or reactor, will prevent alkalinity may be depleted by autotrophic nitrifying and de-nitrifying processes taking place in a biofilter and or the aquarium. Some calcium will be produced . Crushed shell is used in marine aquaria for many decades, aragonite was not always common available. Crushed shells are part of the so called " Bio", used in Europe since the sixties, to stabilise pH and alkalinity, as advised by F.de Graaf. ( ref: FDeGraaf1969 >
Frank De Graaf. Handboek voor het tropisch zeeaquarium. Tweede druk. A.J.G. Strengholt N.V. Amsterdam, 1969. Graaf, Frank de. Marine Aquarium Guide. Harrison, N.J.: Pet Library, 1973. ) In the beginning crushed shells where used in the second compartment after the sand compartment. As nitrification mainly took place in the sand this did not work very good, mainly because the shell grit became bio-fouled. (SSpotte1970 >
Spotte, Stephen. Fish and invertebrate culture; water management in closed systems. New York: Wiley-Interscience, 1970. ) Replacing the sand in the first compartment of the "bio" by crushed shell solved the "biofilter syndrome" in a marine aquarium.
Last edited by a moderator:
SDK
Reef Diver
The old school method for FW snails is to put a piece of cuttlebone in the tank. It’s soft enough for snails to be able to directly feed on for some extra calcium. Apple Snails in particular will be all over it.
They can be found in the bird section of any chain store for a few bucks...
Belgian Anthias
Valuable Member
As in an old school bio a mechanical filter is used the bio-fooling was limited to DOC, preventing the shell grit to provide carbonate and calcium. Bio-fooling can be limited using a MBR ( moving bed).
Belgian Anthias
Valuable Member
A BADES- biofilter( using a nitrifying biofilm growing on a mix of crushed shells and sulphur granulate. produces a lot more calcium as not only nitrification but also denitrification will contribute to the shell grit dissolving rate , stabilizing alk and producing calcium. But only in high nutrient mixed reef systems enough calcium may be produced for to compensate a moderate calcium consumption. [ max +- 4.6 mg Ca may be produced for removing 1 mg NH4-N . This way a very effective "Bio" will not produce much nitrate as most nitrate is used up the moment it is produced, the nitrogen cycle may be closed and the carrying capacity of the system may be increased considerably, as desired.
Only calcium is provided as the carbonate is used.
Only calcium is provided as the carbonate is used.
Last edited by a moderator:
