Pool Opening Instructions: Chemicals

pool-opening-instructions-chemicals-Pool opening, as a process, is pretty much the reverse of the pool closing. It’s a topic that we’ve done before ~ many times.

Today, I’ll skip the procedural stuff on how to open a pool, and focus on how to bring your pool chemistry back after a long winter.

For many, restoring water balance and water clarity can take several weeks. Not so, when you follow these easy pool opening chemical steps and if necessary take some steps to improve water clarity.


Test Kit Type: I don’t care if you use test strips or test kits (sorry, Dr. Pool), but it should be a 5-way test kit, so you can check Chlorine, pH, Alkalinity, Calcium and Stabilizer. Smaller kits won’t check all five levels, and you’ll never achieve true ‘water balance’, unless you want to take a water sample to a local pool store, for an “analysis” and “recommendations”.

test stripsShelf Life: Test your pool water with fresh test strips or test kit. The strips usually have a date code on the bottom of the bottle, and generally last about 3 yrs from manufacturing date. Test kit reagents should be replaced if they had frozen during winter, or been exposed to sunlight, or over 2-3 yrs old.

Accuracy: Test your pool water with precision, to get the most accurate reading you can. If unsure of the reading, read instructions and test again. Other ways to accuracy include using clean testing vials, holding reagent bottles vertical while squeezing out the drops, and taking samples from a depth of 6-10″, and not testing surface water.

intheswim-water-testing-app-Test Log: A small testing log, kept in a tiny note pad, can be surprisingly useful and enlightening, and prevents forgetting the adjustments made in prior days. Write down the readings, and amounts added. You can also use a pool testing app on your tablet or smartphone, for test history and treatment guides.



Your pool water pH level is the most important component of water balance. For spring clean-up, adjust it to the low side; 7.2 – 7.4. If your pH is higher than that, add an acid to lower, and if your pH is lower than 7.2, add a base to increase.



The alkalinity level of your pool water helps keep your pH stable and resistant to change. If Alkalinity is below 80ppm, the pH can fluctuate wildly, raise it with Alkalinity Increaser. If your Alkalinity reading above 120ppm, it can make it hard to adjust your pH; lower it by using our safe Instant Liquid Acid.


If your water doesn’t have enough hardness, it can become aggressive and pull it out of pool plaster or tile grout. Add Calcium Increaser to raise level to 200ppm. If your calcium hardness level is too high, over 400ppm, you can lower by dilution (adding softer water).


instant-pool-conditionerStabilizer, also called Conditioner, liquid or granular, protects the chlorine from the sun. It doesn’t have a great deal to do with water balance, but not having at least 20ppm in the water will allow the sun to burn off your chlorine faster than you can add it! Add Stabilizer if needed, to keep a 30-50ppm level. If your level creeps up in the 50-100 range, you can lower by dilution (adding water).


From the moment you open the pool, until it freezes over during winter, you need to keep a constant level of chlorine in the pool. The final component of water balance is your sanitizer, or chlorine level. After balancing the water, shock the pool with granular chlorine, and then allow the chlorine level to drop to 1.0-2.0ppm. Maintain the level with 3″ chlorine tablets, placed in a floater or feeder.


If your pool is still cloudy, after weeks of running the pump 24/7, perfect water balance and countless dollars spent on chemicals, something’s not right…


  • If your pool has no main drain, hook up a vac head/hose into the skimmer, to improve circulation and draw water from deeper parts of the pool.
  • Check the pool pump, to be sure the strainer basket or impeller isn’t clogged with any little bits, and it’s pumping a full volume of water.
  • how-a-cartridge-filter-worksCloudy water can be a sign of a filter valve problem, with water bypassing the filter. DE filters can pass DE powder through torn grids or cracked manifolds. Cartridge filters can be damaged, or like filter sand, will wear out after a time.
  • If your filter pressure is not rising, your filter is not trapping dirt. Is the pressure gauge working? Does backwashing, or cleaning the filter remove dirt?


  • If your pool still has a lovely green hue, you may need to shock again. Follow label instructions, but hit it hard, until it turns blue-ish.
  • Flocculant can be used, if you are able to vacuum to waste thru a multiport valve. Follow the instructions, and pour in the chemical. Shut off the pump and in 12-24 hrs, everything is laying on the floor, and the water is crystal clear.SeaKlear-PRS
  • Clarifiers are an excellent filter aid. It attracts very small bits into larger clusters – big enough to be removed by your filter. PRS by SeaKlear is our best clarifier.
  • Keep the water balanced, check it daily with a reliable test kit or strip, and make adjustments as needed.


  • Keep your pool clean while trying to clear it. Vac, skim and brush as often as you can to keep springtime out of your pool. infusion-venturi-return-
  • Direct the return eyeball fittings in the same direction, to make a circular water flow around the pool.
  • Check that your skimmer weir is installed and working properly.


~ And that’s about it! Wishing you an easy spring pool opening! Let us know if you have any questions on pool opening chemistry ~

Davy Merino
InTheSwim Blog Editor


Leave a Reply

Your email address will not be published. Required fields are marked *