How To Clear A Green Pool

How to Clear a Green Pool

From time to time, pool owners may experience a green, swampy pool problem.  Many times it will be green or even black in color, and can require a great deal of effort, time and money to return to the point of swimmable.  It is best to never let the pool get to that point, but if it happens, there is a step by step method that will make any swimming pool clean, clear and ready to swim again.

3 Things to clear green water:

Filtration

Chemicals

Labor: cleaning, brushing, backwashing

Step 1:  First you must identify the filter type.  Whether it is a D.E., sand or cartridge filter you must make sure it is clean and running properly.  If the filter is not filtering correctly then the water will never clear up and can cause you to waste a great deal of money in chemicals.

Step 2: Remove large debris.  A leaf net is usually the most efficient way to remove large debris at this stage.  This will temporarily make the pool look much worse due to the stirring up of algae and dirt in the water, but within a few hours it will all settle to the bottom again. (Do not attempt to vacuum large debris through your filter system at this stage because it can severely clog the filter, skimmer lines, and the pipes underground).  Large debris should be professionally vacuumed using a separate power vacuum to save a lot of wear and tear on your filter as well as clogging pipes.  After large debris is netted, blind vacuum pool to waste – not through filter.

Step 3: Test the water. The chemicals all need to be within the given ranges:

Bromine                    2 – 3ppm

Chlorine                    1-3ppm

pH                                7.2 – 7.8

Stabilizer                  30 – 150ppm

Total Alkalinity     100 – 150ppm (vinyl)    80 – 120ppm (plaster)

Calcium Hardness 200 – 300ppm (vinyl)   250 – 400ppm (plaster)

Iron or Copper     Less than 0.3ppm

Phosphates           Less than 100ppb

Step 4: Shock pool using liquid or granular super-chlorinator.  Liquid shock typically works faster, but granular shock is typically more potent. For green pools, shock pool with twice the recommended amount for the gallons in your pool. Then brush down the floor and walls.  Add a quality algaecide.  Systems with sand and cartridge filters should also add a clarifier to speed up collection of dead algae.

Step 5:  Run filter for 24 hours and backwash 3 – 4 times daily. Cartridge filters should be opened up and cartridge rinsed out. Green or cloudy water will clog a filter very quickly so more backwashing will clear up a pool faster.  If using a D.E. filter, make sure the proper amount of D.E. is replaced after every backwash.

Step 6:  Water should turn from green to cloudy to clear.  When cloudy, shock again, and then brush again.

Step 7:  Once water quality improves, debris will then be more easily visible on the floor.  Small amounts of debris can be vacuumed using the pool’s filter system.

Step 8:  Adjust all chemicals to be within the proper ranges and test for phosphates. (See step 3)

Step 9:  Run filter 10-12 hours per day and maintain chlorine level with slow dissolving tabs or a stabilized granular.

Extra Tips: – If these instructions are followed and pool does not clear up within 4-5 days, then filter may not be functioning properly and should be checked by a professional.

– Chemical levels should be tested twice per week to ensure they are within proper ranges.

– Make sure filter is regularly backwashed

– Backwash when filter pressure is 6-8lbs higher than normal running pressure

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