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  Brian McGarry, CBP April 14, 2010 at 4:21am

  We have been using Aruafin's 2K/M with good results. It is a stand alone product, flexible, and provides bidirectional waterproofing in one step vs mulistacoat.
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  Chris Cisneros March 15, 2010 at 11:29pm

  Bill,
  
  You might want to check with the local water agency. Alot of Cities and water agencies are no longer adding copper to the water. Therefore resulting in higher Total Alkalinity in the pools. High total alkalinity results in calcium problems!
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  Kevin Misley February 25, 2010 at 8:29am

  A few things I would like to add to this discussion. First, I would never add calcium to my tile mix to accelerate the curing process. Plaster subs add it of course to speed up curing.(Time watching plasture cure is money) Problem is it bleeds through the finish and is especially noticeable on darker finishes.
  In regards to tile setting in cold or even near freezing conditions, I would recommend a product called Anti-Hydro.(www.anti-hydro.com) It is a liquid additive that goes directly into your water mix at a certain ratio. We also use it when setting coping in these conditions to prevent freezing of the mortar. They have several products to choose from for different applications. Perhaps a better altenative to calcium.
  As far as thinset, a full flex, polymer based material is not a bad choice. It's recommended for glass tile as it properties allow for movement. It's a little more expensive than typical pre-mixed thinset.
  I also think waterproofing the structure prior to setting your tile is key. Thoroseal makes a product that is good for "Positive" and "Negative" applications. A 50# bag Gray (T1018) is available from most mason supplies. To get the full benefit of the waterproofing you must add Acrylic 60 and water to the mix at the proper ratio!
  This product is our preference as it is a easy process to apply.
  I am familiar with Mulasticoat but I don't think it has positive and negative waterproofing features. Plus it's a 2 part process application of the membrane and then an application of a scratch coat. Plus, they recommend waiting 30 days, yes 30 days before applying the product to allow the gunite/shotcrete/concrete to fully cure.
  
  Lastly, the water source at the job site for mixing your materials may have a high mineral content including calcium. Maybe a quick test to determine that may not be a bad idea-just a thought. Most homes in my area that have personal wells or some towns "city" water actually draws from an aquafir have an elevated calcium content.
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  Chuck Beavers February 24, 2010 at 9:54pm

  In my 25 years of setting pool tile I learned the hard way what materials work best for tile bed. Here is the best mix possible in my opinion. Mix in a five gallon bucket 3 inches of water, three parts silica sand, three parts portland, mix with a paddle mixer on a drill for 1 min, three parts silica sand mix for 1 min. Optional calcium depending on climate. I put calcium in everything and do not get the calcium bleed coming through my tile line. I put it in the tile bed, in the grout and in the mortar for the brick coping. Oh and the same mix for the bed work works great for brick coping. Never use spec mix! NEVER NEVER NEVER. Lime is a no no in the pool industry. great product for masons but will not hold up around a pool.
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  Dan Simmering February 24, 2010 at 8:14am

  Not sure where you are located & it seems this problem is prevalent in a lot of areas, I have one residential customer who has fought this problem for years. The source of this customers problem wasnt hard to find...simply in this one case...it was too cold when stonework was done...calcium was added to morter to keep it from freezing as stonework was done...as morter cured calcium pockets formed under stonework on deck...& over time has been a continous leaching problem for them. If your in a warmer setting , as someone else suggested check mix for % of calcium/lime content...may be only option you have
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  David Penton October 17, 2009 at 11:10am

  I agree that the efflorescence is most likely coming from the setting bed.
  
  2 thoughts... could there be movement in the coping allowing for a crack between the coping and the top of the tile? Or could the coping setting bed be getting moisture from the back side, and migrating through and revealing in the tile? Being in the SouthWest we don't have a very significant amount of precipitation. I have seen job photos from other areas of the country where they actually put an elastomeric coating on the back side of the coping, covering the coping material, setting bed, and top of bond beam.
  
  Another thought is to make sure that the formwork that the shotcrete contractor is shooting against is SOLID and can not vibrate which will cause voids in the S/C.
  
  There are some great waterproofing discussions on another site I visit regularly too... http://purewaterpools.com/smf/index.php
  
  Justin Tortorella said:

  David I appreciate your help on this, but I was wondering if you could clarify just a little. I went to the website for thoroseal and saw a couple of products. Right now, we use the mulasticoat on raised pools above grade to add an additional defense with the marble dust and also help limit the efflorescence. However, we are having issues with calcium bleed forming on the grout line below the coping and above the tile. We use an epoxy grout with the tile which has no lime content in it, which leads me to believe that this efflorescence is coming from the setting bed under the coping stone. The product that I think may work, is the thoroseal concrete and masonry sealer. Which is a seal that we will apply after coping and tile is installed and before we proceed with the marbledust. Do you actually use an water reducing additive to your gunite, setting bed and/or thinset material? If you do and this has helped, is it possible that you can let me know which product you use? We had a product from spec mix that they said had a water reducing agent in it that would prevent the efflorescence, but it did not do much. Once again I want to thank you for all the help you have been giving so far.
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  Justin Tortorella October 15, 2009 at 5:40am

  David I appreciate your help on this, but I was wondering if you could clarify just a little. I went to the website for thoroseal and saw a couple of products. Right now, we use the mulasticoat on raised pools above grade to add an additional defense with the marble dust and also help limit the efflorescence. However, we are having issues with calcium bleed forming on the grout line below the coping and above the tile. We use an epoxy grout with the tile which has no lime content in it, which leads me to believe that this efflorescence is coming from the setting bed under the coping stone. The product that I think may work, is the thoroseal concrete and masonry sealer. Which is a seal that we will apply after coping and tile is installed and before we proceed with the marbledust. Do you actually use an water reducing additive to your gunite, setting bed and/or thinset material? If you do and this has helped, is it possible that you can let me know which product you use? We had a product from spec mix that they said had a water reducing agent in it that would prevent the efflorescence, but it did not do much. Once again I want to thank you for all the help you have been giving so far.
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  David Penton October 13, 2009 at 4:31pm

  Thoroseal is a cementicious product that is a waterproofing agent. We usually brush 3 coats on the shotcrete before we begin set the stonework. And by using a quality mortar we have drastically cut down on the calcium blead. (Though I would never promise to a client that you can fully eliminate it)
  
  Mulasticoat is a rubber membrane type of product I believe...?
  
  We have used a similar product to waterproof the backside raised bond beam walls in the past. Thoroughseal though is much easier to work with we have found. With the membrane type product it is so important to get the surface clean, which can be a challenge on a raised planter wall situation. Thoroughseal brushes on easily. Being cementicious though, Thoroughseal is brittle and will crack, whearas Mulasticoat is a flexible membrane which will allow some flex and movement, so there are definite applications for both products.
  
  Make sure you are using whatever product according to the manufacturers spec. though. For instance Thoroughseal is not approved for installations that have negative water pressure, only positive pressure... So make sure you understand which product is appropriate for the specific installation you are working on.
  
  Here is another product line which has been used by others with GREAT results... http://www.laticrete.com/architects/products/waterproofing.aspx
  
  I have heard of guys mixing XYPEX http://www.xypex.com/ in with their mortar beds, and even to the shotcrete itself, but I do not have any firsthand experience with it.
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  Bill Gaias October 13, 2009 at 9:56am

  Thank you for the tip David and I am going to look into this further to see if this might be the cause of our problem. I know that we have been using a preblended mortar and I am currently trying to research the composition of this mortar. The idea about the lime makes a ton of sense. What is this product thoroughseal ? Is this a water proofing agent that is used prior to the mortar or is it additive to the mortar mix?
  
  We have been experimenting with a product called mulasticoat that helps to water proof the shell but i am not certain that is the answer either because we just started using it. Have you had any experience with mulasticoat?
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  David Penton October 12, 2009 at 2:51pm

  We have stopped using low cost pre-packaged "Spec-Mix" type products because they contain a high amount of lime. We are seeing less problems lately. Also we have begun using Thoroughseal on anything which comes in contact with water, except for our waterline tile. I think that the generic masons mix's available at most home improvement centers could be the cause for alot of the problems. A bag of quality mortar runs $10 - $12 locally, as opposed to $4 - $6 for SpecMix.