The ACE Salt Water System in Your Limelight Spa: Setup Levels, Cell Cleaning, and When to Replace the Cell

If your Limelight spa is equipped with the ACE salt water sanitizing system, you already know how easy salt water care can feel. The system generates its own cleaners from a small amount of dissolved salt, the water feels soft, and with proper care it can last far longer between changes than traditionally sanitized water. Like any system, though, ACE works best when you understand what it needs. Most ACE problems come down to three things: salt level, calcium hardness, and a cell that needs cleaning.

This guide covers how the ACE system works, the water levels it needs, how to clean the cell, how to read the system status messages, and the signs it is time for a replacement cell.

How the ACE System Works

The ACE cell sits inside the circulation pump filter of Limelight Collection and Highlife Collection spas equipped with the system. It contains a diamond electrode that generates active oxygen, chlorine, and other cleaners from the salt in your water. According to Hot Spring's ACE owner's manual, the system cleans the water with active oxygen first, before it builds a measurable chlorine level. That is why you may see little or no chlorine on a test strip right after start-up, even though the system is working.

Hot Spring notes that with proper care, ACE lets spa water last up to 12 months between changes. It is important to understand, though, that ACE is not fully automatic. The manual is clear that the spa owner is ultimately responsible for maintaining sanitary water, and heavy users may need to supplement with chlorine granules or MPS.

ACE-equipped spas were offered before the current FreshWater Salt System, and the standard replacement cell, part 76078, is commonly listed for Limelight and Highlife spas from roughly 2010 to 2018. If you are not sure which salt system your spa has, check your owner's manual or the model information in the equipment compartment.

The Water Levels ACE Needs

Hot Spring's ACE manual lists these targets and acceptable ranges:

• Salt: target 1,750 ppm, acceptable range 1,500 to 2,000 ppm
• Calcium hardness: target 50 ppm, acceptable range 25 to 75 ppm
• Total alkalinity: target 80 ppm, acceptable range 40 to 120 ppm
• pH: target 7.4, acceptable range 7.2 to 7.8
• Chlorine: target 3 ppm, acceptable range 1 to 5 ppm

Why Calcium Hardness Matters So Much

Low hardness is the single most important habit for a long cell life. Calcium in the water forms scale on the electrodes, and scale reduces output and shortens the life of the cell. Hot Spring recommends keeping hardness at about 50 ppm, which is far lower than many tap water supplies. If your water is hard, the manual suggests two tools: the Vanishing Act calcium remover, which can remove up to 100 ppm after filling (the XL version up to 300 ppm), or a portable water softener for filling and topping off.

Compatible and Incompatible Chemicals

ACE is compatible with dichlor, MPS, and silver. It is not compatible with bromine or biguanide sanitizers, so never add them to an ACE spa.

Setting the Output Level

The ACE output setting, from 0 to 10, controls how long the cell runs each day. Hot Spring's guidance:

• 0: System off
• 1: Vacation or low output mode
• 2 to 7: Normal use (recommended range)
• 8 to 9: High use
• 10: Maximum output, equal to Boost

Keep the setting as low as possible while still maintaining 1 to 5 ppm chlorine, since running the cell harder than needed shortens its life. For a party or heavy weekend, use the Boost function, which runs the cell for 24 hours before returning to your normal setting, or add chlorine granules for an immediate boost.

The 30-Day Reminder

Every 30 days, the ACE system reminds you to check your water. The green light in the logo and the water care icon flash, and the status message reads Check Water/Confirm Output. Test and balance the water, confirm your output setting, and shock to 5 ppm with chlorine granules. If you ignore the reminder, the manual explains that the system lowers output automatically, to 2 at day 33 and to 1 at day 40.

Starting Up After a Refill

Although ACE water can last up to 12 months, you will still drain and refill eventually, and a careful start-up sets the system up for success. Hot Spring recommends filling with the CleanScreen pre-filter, using soft water if your supply is hard (while keeping hardness at no less than 25 ppm), and cleaning or replacing filters before refilling. Then test and balance pH, alkalinity, and hardness, add salt at about 1 cup per 100 gallons with the jets running, and add chlorine granules to establish a 5 ppm residual. Turn the ACE system on and set output between 3 and 5 depending on spa size. The status can take up to 24 hours to register in the OK range.

Vacation and Low-Use Settings

If you will be away or not using the spa for a while, the manual recommends shocking to 3 to 5 ppm, running the clean cycle, cleaning or replacing filters, and lowering output to 2. For extended trips, set output to 1 for low output mode. When you return, test the water and raise output to your normal setting.

How to Clean the ACE Cell

Clean the cell at least every 90 days, and inspect it monthly if your fill water has hardness above 50 ppm. A dirty cell makes the system work harder, can shorten cell life, and can make the status register low or go offline. Hot Spring's steps:

1. Turn off power to the spa, open the cover, and remove the filter lid.
2. Unscrew the gray filter cap and gently pull the cell out of the filter.
3. Look between the electrodes for scale.
4. Prepare the cleaning solution using the ACE cell cleaner or the cleaning bottle instructions included with the system.
5. Place the cell in the solution so the bottom of the cell is submerged.
6. Soak for about 10 minutes, or until bubbles stop coming from the cell. Continue soaking if bubbling continues.
7. Rinse, inspect, and repeat if needed.
8. Reinstall the cell at the bottom of the filter standpipe, replace the cap and lid, and restore power.

Never insert anything into the cell or pressure wash it. Either can damage the electrodes.

Reading the ACE System Status

The ACE system runs a status test every six hours that considers salt level, cell condition, filter condition, and water temperature.

• OK: The cell and water are working together normally.
• Low: The system is not generating cleaners. The cell may be dirty, salt may be low, water may be cool, chlorine may be high, or filters may be dirty. The reading is lower in cooler water, so make sure the water is above 95 degrees F before testing.
• High: Salt is too high and the system is not generating cleaners. If the reading is less than halfway into the red, drain about 25 percent and refill, then retest. If it is more than halfway, drain completely and restart.

You may see an Offline - Circ Pump message when the Summer Timer is active, since ACE is disabled for 8 hours during that time. Offline - Inspect Cell/Check Salt means exactly that: clean the cell and test salt.

When to Replace the ACE Cell

Hot Spring puts average ACE cell life at two to three years, depending on usage, source water, and maintenance. The clearest sign of a worn cell is a status that keeps reading low even after you have confirmed salt level, cleaned the cell, cleaned filters, and tested with warm water. At that point, the manual suggests it may be time for a new cell.

To get the most life from a replacement cell, keep hardness near 50 ppm, clean the cell on schedule, keep filters clean (Hot Spring recommends every 30 days for ACE spas), and run the lowest output that keeps chlorine in range.

Frequently Asked Questions

How long does an ACE salt cell last?

Hot Spring lists average ACE cell life at two to three years, depending on spa use, source water, and how well the cell is maintained.

What salt level does the ACE system need?

The target is 1,750 ppm, with an acceptable range of 1,500 to 2,000 ppm. Add salt one cup at a time with the jets running, about 1 cup per 100 gallons, and verify with salt test strips.

Why is there no chlorine reading after I started up my ACE system?

ACE cleans with active oxygen before it builds a chlorine residual. If there is no chlorine after 24 hours, add chlorine granules to reach about 3 ppm and give the system a few days. If readings stay low, increase the output setting or check salt.

How often should I clean the ACE cell?

At least every 90 days, and more often if your water is hard. Inspect monthly if your fill water is above 50 ppm hardness.

Can I use bromine with the ACE system?

No. ACE is not compatible with bromine or biguanide. It works with dichlor, MPS, and silver.

The ACE system rewards a little consistency. Keep salt near 1,750 ppm and hardness near 50 ppm, clean the cell every 90 days, respond to the 30-day reminder, and keep the output as low as your chlorine readings allow. Your Limelight spa will reward you with soft, clear water and a cell that lasts as long as possible.