Calcium reactor substrates - still an issue

[Greg Hiller]

For probably 5-7 years or so I was using Two Little Fishes Reborn as a calcium reactor substrate. I was quite happy with it. It was a large size and didn't turn to mush easily. I could generally dissolve down to about 1/2 of the original volume of the substrate before having to clean the reactor and recharge it. Unfortunately, about 2 years ago, during the pandemic, I think that flights out of the Indo-Pacific were less frequent, and TLF had trouble supplying Reborn. For a while I switched to using old coral skeletons from my old tank that I'd bleached out and rinsed well. That worked quite well and I limped along for about the 1st year of the pandemic. Eventually Reborn became available again, but it was no longer the large size. It was smaller and kind of brownish in color and still not always available. Seemed not as good to me and even more expensive than in the past. I tried another substrate recently, but it seemed to do the "turn to mush" thing, so not happy with that either.

I was at a local beach recently and noticed that thick clam shells were everywhere. They were relatively clean and it was easy to fill a bucket with them in just an hour or so. danged heavy was that bucket. Anyhow, I thought I might give them a try as a calcium reactor substrate. Smashing them up with a sledge hammer was super easy. Since in some cases there was a bit of protein still on them, usually around the hinge region I decided I'd soak them for a bit in a dilute bleach solution. I did put a few in my calcium reactor at the top just to see if they dissolve, but I have a few questions before I try a larger test:

1. Do you think they will need a lower pH to dissolve? - Are they a form of calcium carbonate that is more stable than aragonite?
2. Do you think they will release more nutrients than other calcium reactor substrates?

Of course I could perform the tests I did so long ago to compare substrates, but I thought I'd ask your opinion first (maybe I'm lazy in my old age!).

 

[Randy Holmes-Farley]

Hey Greg. Great to see you!

Clam shells are apparent a mix of calcite and aragonite. You'd likely find this article interesting:

How are seashells made? - Woods Hole Oceanographic Institution

One of the most striking features of our beaches is seashells. Their whorls, curves, and shiny iridescent insides are the remains of animals. But where do they come from?

www.whoi.edu

So it may start out at a similar pH and then need it lower if the aragonite dissolves away.

I've certainly heard folks claim they may be high in phosphate, but I could not find actual evidence of this in a quick search.

 

[Dburr1014]

Hey Greg. Great to see you!

Clam shells are apparent a mix of calcite and aragonite. You'd likely find this article interesting:

How are seashells made? - Woods Hole Oceanographic Institution

One of the most striking features of our beaches is seashells. Their whorls, curves, and shiny iridescent insides are the remains of animals. But where do they come from?

www.whoi.edu

So it may start out at a similar pH and then need it lower if the aragonite dissolves away.

I've certainly heard folks claim they may be high in phosphate, but I could not find actual evidence of this in a quick search.

I also heard high in phosphate but never sure.
Let us know how you do!

 

[atoll]

I have noticed mussel and esp barnacle shell dissolves well. However I have never tried them in a calcium reactor. Any thoughts? @Randy Holmes-Farley

 

[jda]

This is just anecdotal from my experiences, but clams shells do not dissolve as easily as reborn or ARM does. I put some in my reactor and they hardly changed while the other media got down to 50%, or so.

I use the new ARM and it is fine. It keeps my big three going well and CaribSea says that it has other traces in it that I would have no way of verifying. I find ARM and the older Reborn to be pretty much an even exchange. The both melt at similar bubble and drip rates for me, as well - I don't measure reactor pH and do not find it useful, so I don't know about pH to melt.

 

[taricha]

I've certainly heard folks claim they may be high in phosphate, but I could not find actual evidence of this in a quick search.

I think in a convo with @Lasse, I saw @Sallstrom share data that mussell shells released significant PO4 under low pH. But so did coral skeleton grown from the aquarium. Bought coral rubble released much much less, like less than 1/10th of the mussell and grown coral.

 

[Dburr1014]

I'll bring up the question,
Do clams and mussels all build the shell the same way? Is it the same ratios of sand, carbonate, po4, ect?
Maybe one type of shell is better than another.

 

[Lasse]

I think in a convo with @Lasse, I saw @Sallstrom share data that mussell shells released significant PO4 under low pH. But so did coral skeleton grown from the aquarium. Bought coral rubble released much much less, like less than 1/10th of the mussell and grown coral.

Yes your right - @Sallstrom has done some investigation of this - but - it is really a problem if they do?

Sincerely Lasse

 

[atoll]

Yes your right - @Sallstrom has done some investigation of this - but - it is really a problem if they do?

Sincerely Lasse

That's the real question Lasse and just how much compared with say the various foods we feed.

 

[Snoopy 67]

Greg,
MTC, (now gone) used to recommend Florida crushed coral for their reactors.
You will get mush after a while but for me it was not that bad.

 

[atoll]

Greg,
MTC, (now gone) used to recommend Florida crushed coral for their reactors.
You will get mush after a while but for me it was not that bad.

I wonder if the mush would have continued to dissolve.

 

[Greg Hiller]

Just to follow up on this thread. I've been filling my calcium reactor with about 1/3 quahog (clam) shells from the beach in Revere, MA (near me), 1/3 recycled Monti and Acropora skeletons from my tank (I just beach them out and rinse then dry until no bleach smell), and about 1/3 of the calcium carbonate reactor substrate from Tunze (a reasonably priced material). The clams dissolve just fine. For a little while I was running them by themselves in a separate, small calcium reactor. I tested the effluent (and measured the volume flowrate) for alkalinity from that reactor for a while and it seemed to be supplying calcium and alkalinity just fine. I now just mix them into my main calcium reactor.

Even with all the other stuff in that reactor (that I thought might dissolve easier) the clam shells continue to dissolve just fine. They do get a little "sharp" after dissolving, so don't cut yourself when you are emptying your reactor. I put the shells into a cardboard box (or an old salt bucket) with a brick at the bottom, then smash them with a sledge hammer. Sounds like a lot of work, but it's not. It's actually therapeutic...smashing stuff! Maybe I need therapy! Once they are down to the size of quarters or half dollars I put them into the reactor. I don't generally put in the dust. I'm sure you could add them without the smashing, but I wanted to increase the surface area a bit, and make sure I still had good recirculation flow in the calcium reactor.

 

[Dburr1014]

Just to follow up on this thread. I've been filling my calcium reactor with about 1/3 quahog (clam) shells from the beach in Revere, MA (near me), 1/3 recycled Monti and Acropora skeletons from my tank (I just beach them out and rinse then dry until no bleach smell), and about 1/3 of the calcium carbonate reactor substrate from Tunze (a reasonably priced material). The clams dissolve just fine. For a little while I was running them by themselves in a separate, small calcium reactor. I tested the effluent (and measured the volume flowrate) for alkalinity from that reactor for a while and it seemed to be supplying calcium and alkalinity just fine. I now just mix them into my main calcium reactor.

Even with all the other stuff in that reactor (that I thought might dissolve easier) the clam shells continue to dissolve just fine. They do get a little "sharp" after dissolving, so don't cut yourself when you are emptying your reactor. I put the shells into a cardboard box (or an old salt bucket) with a brick at the bottom, then smash them with a sledge hammer. Sounds like a lot of work, but it's not. It's actually therapeutic...smashing stuff! Maybe I need therapy! Once they are down to the size of quarters or half dollars I put them into the reactor. I don't generally put in the dust. I'm sure you could add them without the smashing, but I wanted to increase the surface area a bit, and make sure I still had good recirculation flow in the calcium reactor.

Have you checked the po4 content of the effluent?
Just curious, I thought the consensus was bi-valves add lots of phosphate.
It would be nice to know.

 

[Greg Hiller]

No haven't checked the PO4. I don't have many test kits anymore, not worth the trouble. I check salinity once in a while with a refractometer. I make my own alk test reagent and test every few days, and I check calcium and magnesium about once per 6 months, but other than that I just use my eye on my tank.

 

[schprock]

BRS did an investigation on phosphate in effluent of various media. I had phosphate that was creeping up but switched away from reborn and phosphate has been trending down.

BRStv Investigates - Are Calcium Reactors Acting As A Phosphate Factory In Our Reef Tanks?

An unassuming ICP test reveals a surprising correlation between rising phosphate levels in your reef tank and calcium reactors.

www.bulkreefsupply.com

 

[Dan_P]

I wonder if the mush would have continued to dissolve.

What is the “mush”? Very fine undissolved minerals?

 

[atoll]

What is the “mush”? Very fine undissolved minerals?

Yes like a white mud.

 

[Dan_P]

Yes like a white mud.

I see. So here’s another question.

Could much of the stuff vacuumed from substrate also be this mush, generated by the action of CO2 and organic acids on aragonite sand and generated by microorganisms in the substrate? I believe @taricha has probe the sand but can’t remember he has thought along these lines.

 

[Randy Holmes-Farley]

I see. So here’s another question.

Could much of the stuff vacuumed from substrate also be this mush, generated by the action of CO2 and organic acids on aragonite sand and generated by microorganisms in the substrate? I believe @taricha has probe the sand but can’t remember he has thought along these lines.

Natural coral skeletons also contain organic matter. That might be part of the residue:

https://www.researchgate.net/publication/241061676_Associated_water_and_organic_compounds_in_coral_skeletons_Quantitative_thermogravimetry_coupled_to_infrared_absorption_spectrometry

 

[taricha]

What is the “mush”? Very fine undissolved minerals?

Yes like a white mud.

Could much of the stuff vacuumed from substrate also be this mush, generated by the action of CO2 and organic acids on aragonite sand and generated by microorganisms in the substrate? I believe @taricha has probe the sand but can’t remember he has thought along these lines.

Most of the stuff from my sandbed that vacuuming removes is super-fine white/grey dust/silt. It is almost entirely soluble with HCl and doing a Ca test on the dissolved stuff points to it being around the expected Ca % for CaCO3.
Why the dissolution of aragonite sand under mid-7's pH conditions in my sandbed leads to the endpoint of fine CaCO3 dust I dunno, but probably too far an aside for this thread
I've never used a Ca Reactor, but my guess is that with the pH in the reactor going much lower than in my sandbed, the mush left behind is likely acid-insoluble - and thus maybe not like most of the the dust/silt that accumulates in my sandbed.