Safe Skimmer Equalizer Lines

Skimmer equalizers should be required when skimmers are the sole source of suction for a pump.

We have proven that main drains are not required for proper circulation.  It is irresponsible to suggest the elimination of equalizer suction outlets as well, and thereby the protection for multi-thousand dollar pumps and proper water sanitization.

Low Flow Conditions

Low flow situations can occur from low water levels, weirs that become askew from kids playing with them, excessive waves, debris (goggles) and wear.  The baskets can become blocked due to latex bathing caps, inflatable toys, paper napkins, leaves or other unexpected debris.

When skimmers are the sole source of suction for a pump, the lack of equalizer suction outlets will deadhead the pump or cause a run dry condition, if the skimmers become clogged or inoperative.  The expense of repairing damage to pumps from "run dry" conditions, will become the burden of the designer or installer, because the damage is easily preventable through the use of equalizer suction outlets.

Skimmers

Most skimmers have flow ratings of only 75 gpm.  Skimmers should always be installed in a minimum of pairs, even more if the designed flow rate of the system demands it.   

Equalizers should be installed in a configuration that limits their line velocities to no more than 3 FPS and provides suction entrapment protection in compliance with VGBSA (some jurisdictions have a restriction of only 1.5 FPS).  Since anti-entrapment covers are derated when wall mounted, more than two equalizer inlets may be required to maintain a compliant flowrate.  Equalizers suction outlets should be installed with a minimum of three feet of separation and with the proper sump configuration.

 

Don't merely rely on Variable Speed Pumps

Variable speed pumps have an inherent design flaw.  When they shut down in a “self protection mode” due to loss of prime or low flow conditions, they do not provide an alert to their attached control systems or a remote control panel.   

Critical filtration and sanitization systems may become locked out for extended periods of time without any indications or warning signals.   In commercial pools or spas, this could quickly result in unsanitary and unsafe water conditions.  When system flow is critical to prevent facility damage (e.g. operation during freeze conditions), inoperative pumps are unacceptable as more severe damage to the facility may occur.

The Solution is Inexpensive

 

Properly installed with float valves and equalizer line check valves, equalizers will be dormant most of the time.  Only an equalizer check valve (pop-it check valve) in the skimmer can prevent suction on the equalizer line.  A float valve by itself will actually divert some suction to the equalizer lines.  

Therefore, float valves AND equalizer check valves should be utilized together, to prevent suction on the equalizer lines, except in critical skimmer low flow situations.

Contact the author, Paolo Benedetti of Aquatic Technology Pool and Spa at: info@aquatictechnology.com or 408-776-8220. 
Visit his website at: www.aquatictechnology.com. 
All Contents © Aquatic Technology Pool & Spa, 2013. All rights reserved.

Galvanic Corrosion and Electrolysis in Saltwater Pools

When galvanic corrosion, electrolysis or staining occurs in saltwater pools, a SACRIFICIAL ANODE is not the placebo everyone is seeking. 

Marine Applications

On a boat, a sailor does not care if the anode erodes, or if the anode's metals dissolve into the water (ocean).  The anode on a boat is a lot cheaper than the wiring, prop or shaft.  It prevents the corrosion of the precious components, by SACRIFICING itself instead. 

Swimming Pool Application

But, placing a sacrificial anode in a swimming pool is doing the same thing as on a boat.  One is merely offering a SACRIFICIAL metal for the galvanic corrosion to attack, instead of the precious components. 

So instead of plating surfaces with copper, you will be plating them with zinc or magnesium from the anode.  The sacrificial anode will save the copper, but it will not stop the staining or plating of the stainless steel components.  That will NOW occur with the metal from the anode.  This is exactly why anodes need to be periodically replaced - they are sacrificed.

Sacrificial anodes are not the solution to the damage caused by galvanic corrosion or electrolysis.

Bonding Grid

The equipotential bonding grid does not prevent galvanic corrosion.  In fact, if there is stray voltage finding it's way to the pool through the property's CONTINUOUS GROUNDING SYSTEM, the equipotential bonding grid may actually be feeding voltage to the pool's metallic components. 

The bonding grid can actually function as either the electrode or cathode, depending if there is stray voltage present on the property, thereby energizing the bonding grid.  Alternatively, it can be providing a path to ground, where the equipotential bonding grid and the grounding grids are intentionally cross connected - pumps, heater's, panel boards, etc.

A Solution

For these very reasons, many pool builders that I know and I, have ceased installing salt systems.  We now promote the micro-dosing of bleach via a ORP/pH Controller, augmented by a commercial sized ozone generator and contact chamber.


Contact the author, Paolo Benedetti of Aquatic Technology Pool and Spa at: info@aquatictechnology.com or 408-776-8220. 
 Visit his website at: www.aquatictechnology.com. 
All Contents © Aquatic Technology Pool & Spa, 2013. 
All rights reserved.

Shotcrete Swimming Pool Reinforcing Steel Placement

Reinforcing steel - the bones that hold the body together.

Why does shotcrete require reinforcement?

Concrete is very high in compression, but week in tension.  That means that concrete does not flex well.  However, steel is very high in tension and weak in compression.  So this is a marriage made in heaven - each compliments the other.

Placement - where does it go?

The placement of the reinforcing steel within the shotcrete wall is very critical.  The structural engineer may specify that the steel be installed closer to the outside or the inside of the concrete, depending upon the anticipated loads.

Incorrect placement of the steel will result in a structure that is not as strong as the engineer intended.

Lap Splices - Contact or Non-Contact?

Pieces of reinforcement steel come in finite lengths.  This means that splices will need to occur.  But how do you to create proper splices?

Remember, the steel exists to reinforce the concrete.  Therefore, the bars of reinforcing steel do not have to make contact with each other when they are spliced.  Because shotcrete is applied with air at tremendous velocities, the steel needs to be arranged to allow the concrete to completely encase the reinforcement.  If bars begin to create congestion in an area, then it is almost guaranteed that there will be voids and honeycombs behind them.

ACI 506R-95, Guide to Shotcrete, Section 5.4.2 states that non-contact lap splices shall be utilized to prevent this very occurrence.  This is the standard and code across the United States, since the American Concrete Institute (ACI) standards have been adopted and incorporated into the International Building Code (IBC).  The IBC is the building code for the entire United States.  

Non-contact lap splices shall also be spaced so they do not exceed the ACI guidelines.  Otherwise, excessive spacing could create unreinforced areas of concrete.

Contact the author, Paolo Benedetti of Aquatic Technology Pool and Spa at: info@aquatictechnology.com or 408-776-8220. 
Visit his website at: www.aquatictechnology.com. 
All Contents © Aquatic Technology Pool & Spa, 2013. 
All rights reserved.

Concrete Coloring and Pigments

Concrete pigments for coloring concrete

Quality Materials

In swimming pool environments, poor quality pigments in concrete will be susceptible to fading and discoloration.

There are many criteria that go into quality pigments.  The size of the fines (granules), purity of the oxides, quality control of the color and synthetic or natural ingredients, all contribute to the durability and rendition of the color.

Use and experience with various brands, will identify the best performers.

Water Chemistry

Improper maintenance of the swimming pool water chemistry, the extremes can also cause aggressive or scaling conditions.

Maintaining water chemistry records is a great way to prevent water chemistry from being blamed as the cause of concrete discoloration.

Sealers

Properly sealed concrete will resist most chemical attacks or poor water chemistry, long enough to clean up the spill.  Penetrating sealers are the best, as they let the concrete breath, resist most stains and do not change the sheen of the surface.  They also do not contribute to slippery conditions.

Use quality materials that are specified by experienced consultants or contractors.

Contact the author, Paolo Benedetti of Aquatic Technology Pool and Spa at: 
info@aquatictechnology.com or 408-776-8220. 
Visit his website at: www.aquatictechnology.com. 
All Contents © Aquatic Technology Pool & Spa, 2013. 
All rights reserved.