Is Quickrete Quick Setting reef safe?

Fresh concrete will absorb hydrogen ions in the water, leaving a higher ratio of hydroxide ions, thus making the water more basic. It can take up to six months for the concrete to be "cured" and stop altering your pH. The change in pH should be negligible using something as small as frag plugs, but if making your own rocks for example, it needs to be cured outside the tank.

If you're worried, just keep an eye on your pH.
 
What would probably be best would be Lime Mortar made with calcium carbonate as the lime, then (hopefully) crushed coral as the aggregate:
https://en.wikipedia.org/wiki/Lime_mortar

But given the Home Debit/Lowes options it would be nice to have a sort of guide/lines of which options are best/worst, how to know, etc.

"Portland cement, the chief ingredient in today's masonry mortars, sets by adding water, which is called a hydraulic action. Using a quite different process, lime sets over time through a reaction with air, called a carbonation process.

Limestone, chalk and seashells are essentially calcium — calcium carbonate to be precise. Lime is derived from heating limestone (or chalk or sea shells) at high temperatures, which drives off the carbon dioxide that is part of its chemical composition and turns the limestone into quicklime, or calcium oxide.

When water is added to the quicklime, it generates heat, called an exothermic reaction. In the trade, we call this process "slaking" the lime. If the lime is made into a powder at this stage, it will become the lime you may have seen sold at masonry supply stores, called hydrated lime. However, if you add excess water during the slaking process, the lime will turn into putty. (To some confusion, hydrated lime and lime putty are chemically almost the same, and both are referred to as "calcium hydroxide.")

The longer lime is left as putty, the more workable it will be in the end. Over time, the lime putty undergoes a process whereby the lime crystals reduce in size upon aging and transform into small plates that slide when rubbing against each other. This action allows more water to be absorbed, giving lime the property of being highly workable, or having "plasticity."

While Portland cement hardens due to the chemical reaction with the water, if stored in a sealed container, lime putty will remain workable and soft indefinitely. Lime will harden over time only when it comes in contact with carbon dioxide and moisture.

Once a lime-sand mortar is mixed and placed in the wall, the water will begin to absorb or evaporate and the mortar will appear to set after several hours. However, the lime then begins to react with the carbon dioxide present in the air and harden, a process that actually will take years to complete. A simplified explanation is that, chemically, the lime is returning to its former state of being a stone.

A more complex explanation is that the carbon dioxide and moisture convert the lime on the surface of the joint back to calcium carbonate. The open pore structure of the lime-based mortar allows the carbonation process to take place deeper in the joint over time. "
http://www.masonrymagazine.com/1-06/limemortar.html

"Mortar Types

Since each cement has different good and bad qualities, most common mortars combine both types of cement. There are 5 main types of mortar, suitable in different applications, each with different strengths, properties and applications.

Type M – 3200 PSI – 100% Portland
Type S – 2200 PSI – 67% Portland – 33% lime
Type N – 1400 PSI – 50% Portland – 50% lime
Type O – 1000 PSI – 33% Portland – 67% lime
Type K – 750 PSI – 100% lime

Bricks and wall stones are usually laid in Type N. This 50-50 mix combines the good qualities of the Portland (strength and fast set time) with the flexibility, permeability and workability of lime.

Type M (pure Portland) or Type S must be used for anything exposed horizontally to the elements, such as a stone patio, door threshold or wall coping. This is because water pooling and salt will quickly erode the surface (usually within one year) if the mortar is Type N or lower.

Types O and K are rarely used (Type O is usually for glass block and Type K is practice mortar).

Types of Lime

The element that gives the cement strength is the clay content. Portland cement is about 30% clay based, while lime is usually about 5% clay. However there are three basic strengths of lime mortar, depending on the amount of clay present. The closer the clay percentage gets to 30% the closer it is to a Portland cement since the strength will be the same."
http://stonehengemasonry.ca/lime-vs-portland-cement-which-is-better/

"Type K mortar
This uses a 1 / 3 / 10 mix and results in a mortar with but a 75 psi compressive strength. Type K is useful only in historic preservation situations where load bearing strength is not of importance and the porous qualities of this mortar allows very little movement due to temperature and moisture fluctuations. This aids in prolonging the integrity of the old or even ancient bricks in historic structures.

To get 1 cuyd of K mortar, you need 27 cubic feet of the components in a 1 to 3 to 10 proportion.

Portland cement 1.93 cuft
Hydrated lime 5.79 cuft
Sand 19.29 cuft
Total 27 cuft

Based on the ASTM densities, this gives you 181.42 lbs of Portland cement, 231.6 lbs of hydrated lime and 1,543.2 lbs of sand.

To put together a single cubic yard of type K mortar, you need to buy:

1.93 bags of Portland cement
4.632 bags of hydrated lime
0.7716 tons of sand


Straight lime mortar
This uses a 0 / 1 / 3 mix and is used now only to recreate the construction and review the methods of times past or maybe for purely visual purposes. This mortar was made before Portland cement was available in many areas and so this is what was used. Sometimes you'll see straight lime mortar called "L" mortar (for lime) but this is not designating it as "type L" mortar as in the MSNOK types. There is no "type L" mortar.

To get 1 cuyd of lime mortar, you need 27 cubic feet of the components in a 0 to 1 to 3 proportion.

Portland cement none
Hydrated lime 6.75 cuft
Sand 20.25 cuft
Total 27 cuft

Based on the ASTM densities, this gives you no Portland cement, 270 lbs of hydrated lime and 1,620 lbs of sand.

To put together a single cubic yard of lime mortar, you need to buy:

No bags of Portland cement
5.4 bags of hydrated lime (50 lb bags)
0.81 tons of sand"
http://www.ribmc2.com/estref/popular_conversion_files/masonry/mortar.htm
 
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Oh, one way I've gathered to add the pits is to use rock salts. Although I havent yet figured out how they manage it / to do it economically the big MMLR MFG outfits...
 
I don't need that much product though. 5.4 bags of hydrated lime. I need a small amount. =(

I have the rock salt, I've made rocks before but never tried the quick setting cement. I read it a long time ago from Mr.Wilson that he uses it, or something like it, when he builds large rocks for public aquariums and people's houses. At least I believe it was Mr. Wilson. It is buried in the 5 page split of DIY MMLR. I guess I just need to go through it again. I was hoping I didn't have to. It's sooooooo long.
 
Yes, supposedly Qwickwall is aquarium safe once cured. I will be using very little just to hold some rocks together.
 
You may get a pH spike when going from fw to sw so you may want to mix up some sw and place it in a bucket to test after a few days.

Doubtful if this will be an issue though.
 
MarineGirl411 said:
I don't need that much product though. 5.4 bags of hydrated lime. I need a small amount. =(

I have the rock salt, I've made rocks before but never tried the quick setting cement. I read it a long time ago from Mr.Wilson that he uses it, or something like it, when he builds large rocks for public aquariums and people's houses. At least I believe it was Mr. Wilson. It is buried in the 5 page split of DIY MMLR. I guess I just need to go through it again. I was hoping I didn't have to. It's sooooooo long.
Click to expand...

Since most cement is Portland cement (a manufacturing process) it needs to be more specific. What you want to use in an aquarium (for any purpose) is a Low Alkali White Cement (pool builders supply) Using anything else that is commonly available can lead to some rather bizarre pH issues. (very long stabilization times and such.) Riverside (a brand) manufactures such a product. Not available at big box stores.

I don't know where Mr Wilson has worked, but I have been involved with both Birch and The Smithsonian, and recently in Monaco. These systems are large open systems (open to the ocean) and the volumes of water moved make such things of little consequence, but care is still taken. Small closed systems, like home aquariums, are a different story. I don't generally get into specifics of public aquariums as they are different animals, other than to say plenum systems are a sound method as that is what they use for the most part.

If you are inclined to DIY rock, make the rock in such a manner that it fits together and does not fall down. Takes a little more thought, but saves worrying about how to bond them together.

As usual I say: Use inert Aragonite sand, Low Alkali White Cement, and an inert filler, rather than 'ert' rock salt and oyster shell, and just any 'Portland Hydraulic Cement.' This is the method and materials that started the DIY Rock craze. Now no need to go through 5 splits of folks trying to build a better mouse trap. ;)
 
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