Terrible Advice Tuesdays: A Hidden Danger When Moving A Saltwater Tank
Terrible Advice Tuesdays: When you move a saltwater tank, you have to wait several months for the new sand bed to leach out all the calcium and magnesium it contains or else you’ll kill your corals.
The rest of the story: Oh man. This is bad news if you are dosing calcium or magnesium in your tank because calcium and magnesium obviously kill corals!
This advice is ludicrous on many levels. I’ll break it down for you:
First, sand doesn’t break apart when it gets put in a saltwater tank. In fact, to get sand to dissolve into saltwater, you will have to drop your pH to a very low level (pH 6.5-6.7) like in a calcium reactor. The 7.7-8.5 pH range of saltwater tanks won’t do anything to do your sand bed.
Second, calcium and magnesium aren’t harmful to corals. Think about it, what are hard corals made up of…calcium! And lots of saltwater hobbyists including myself dose magnesium into their tanks. If these elements killed corals, we would have stopped dosing them a long time ago.
Yes, very high calcium and magnesium could harm corals. Simply putting in new sand into your recently moved saltwater tank isn’t going to throw your calcium and magnesium levels out of whack so don’t worry.
Bonus tip: As I recommend in my Moving and Upgrading a Saltwater Tank guide, I recommend you replace your whole sand bed when you move or upgrade a tank. The amount of junk in your sand bed can cause nitrate and phosphate issues when it gets stirred up during the moving process. The price of new sand is much less compared to the headache of long term nitrate and phosphate issues.
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Hi Mark,
Another tip that has saved me from failure, I recently asked you if I could reuse the sand that I had removed from my tank, this bonus tip has obviously answered my question, so Thanks again.
What has happened to the videos, please keep them coming.
Laurie
I recently downsized from a 55g to a 29g. Other than a week long cyano outbreak, keeping my old sand hasn’t done anything to my tank. In fact my corals are growing faster now than they ever did before. But I believe the reason I had no issues (besides that first week) was that I siphoned off the sand repeatedly before transferring it and I have a sand sifting goby that is constantly stirring the sandbed for me…. The cyano could also have been caused by my adjusting to feeding fewer fish and the small amount of die off (bacterial) I would have gotten from the change in aquascape/flow.
Sorry, Mark. Here’s a quote out of “Book of Coral Propagation” by Anthony Calfo, page 28. “However, oolitic aragonite has the wonderful benefit of dissolving rather quickly; in ordinary systems it has a half-life of approximately 18-24 months (aragonite can dissolve at a pH as high as 8.2).” Compositional calcite material (crushed shell, rubble, crushed coral, etc) does not dissolve unless the pH drops to near or below 7.6.
But I do agree that you don’t have to worry about high levels of calcium and magnesium from it.
Mike J…the more recent articles suggested otherwise:
James Fatherree: (http://www.advancedaquarist.com/2011/10/chemistry) “It’s been said a million times that aragonite helps buffer aquarium water, or helps maintain calcium concentrations, while other (carbonate) substrates do not. However, to the best of my knowledge this simply isn’t true.”
older, yet still relevant:
Randy Holmes-Farley: (http://www.advancedaquarist.com/2002/7/chemistry) “calcium carbonate will not dissolve in the water column of normal marine aquaria.”
Neadless to say the terrible advise is complete BS…
Regarding the discussion of substrates dissolving releasing carbon ions:
Calcium carbonate that dissolves in water not at a very low PH is called kalkwasser. If the calcium carbonate in our substrates did dissolve at normal tank PH levels we would not be able to use it in our tanks as it would be the same as having kalk in our DT.
Now if you have a calcium reactor on your system I suspect you could see some tiny amount of the substrate dissolve due to the addition of low PH effluent from the reactor. This would explain the buffering effect some people report from calcium carbonate rich substrates. From that there could be additional calcium ions released in the process.
Overall I do not see this happening very quickly or to a massive degree without having some fairly unusual setups.
I just switched tanks 2 weeks ago. Had a 55 tal and switched to a 54 corner. Moved water into buckets, moved sand to new tank, filled with 30 gallons old water and had 15 new that i made a few days before, let it settle for a few hours, built aquascape, added fish, inverts, and coral and fired it up. Everything is doing great and loving the new setup. Only problem I had is the sand being so fine it has been blowing around with the amount of flow i had. I put a valve on the inlet, filter sock to catch the stuff, and changed powerhead that was 1300 gph to 2 smaller ones and everything is looking great. I plan on adding a bag of indo-pacific sand to add the black being the rest of the setup is black and my sand from the previous tank only made a 1 1/2 in sand bed. My skimmer is going producing alot of bubbles and not much skimate tho. Guessing its cuz there is not much crap yet.
Biological processes in the sand can cause the sand to break down. Just one example is nitrification. To go from NH3 to NO2 the bacteria take O2 and HCO3, oxidize the NH3 to NO2 and release CO2 and H+. Then the CO2 combines with water, making H2CO3, which releases H+ as well. All these H+ ions in you sand bend can and does lower the pH in the sand bed enough to cause some disintegration of the sand bed. The first article that Mark cited refers to the second article he cited. The Reef Aquarium by Sprung and Delbeek has a section on this topic and specifically says that you will have to add sand to your aquarium every few years, because of it dissolving and compacting, if you want to maintain a certain depth.
There are factors in the ocean that dissolve Calcium Carbonate; like colder water, more pressure, and CO2 in water 4 – 6 km deep. I don’t have the time right now to delve real deep into this. Just wanted to point out that if Calcium Carbonate didn’t dissolve at a higher pH we wouldn’t have a lot of life in the ocean. Here’s a chart taken from Wikipedia, it dissolves a lot less, but it still does.
With varying pH[edit]
The maximum solubility of calcium carbonate in normal atmospheric conditions (\scriptstyle P_{\mathrm{CO}_2} = 3.5 × 10−4 atm) varies as the pH of the solution is adjusted. This is for example the case in a swimming pool where the pH is maintained between 7 and 8 (by addition of sodium bisulfate NaHSO4 to decrease the pH or of sodium bicarbonate NaHCO3 to increase it). From the above equations for the solubility product, the hydration reaction and the two acid reactions, the following expression for the maximum [Ca2+] can be easily deduced:
[\text{Ca}^{2+}]_\text{max} = \frac{K_\text{sp}k_\text{H}} {K_\text{h}K_\text{a1}K_\text{a2}} \frac{[\text{H}^+]^2}{P_{\text{CO}_2}}
showing a quadratic dependence in [H+]. The numerical application with the above values of the constants gives[citation needed]
pH 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.27 8.4
[Ca2+]max (10−6mol/L) 180 71.7 28.5 11.4 4.52 1.80 0.717 0.519 0.285
[Ca2+]max (mg/L) 7.21 2.87 1.14 0.455 0.181 0.0721 0.0287 0.0208 0.0114
Hey mark
i have a nuvo 16 gallon open top tank. i know its 1 inch of fish per 3 to 5 gallons. right now i just have a clown fish. can you recommend some cleaner fish for my small tank. im thinking a goby to clean my sand but i heard they jump. keep up the good work.
Hey Mark, I just wanted to say thanks for all the videos. I just started a new system and a YouTube Channel (My Pristine Marine) to document the build. In the first video I give you a shout out. You can find the videos by typing Ocean Motion Reef Build in the search browser in YouTube. Thanks again!