Should I drain my pool to get rid of algae? Yes, you can because it saves time and money, but only if you do it properly. Use the main drain in your pool and drain water through the filter pump. Or rent or borrow the pump, place the hose down the street or storm drain, and drain.
Why it's never a good idea to drain your pool
In fact, having green pool water is actually a good chance to practice everything that you've learned about pool chemistry and maintaining your pool water.
Don't drain and acid wash your pool to remove black spot algae because it will just come back again. Draining the pool is not effective because the algae also lives in the pipework, solar heaters, filter and pump.
You can get rid of algae quickly by vacuuming and brushing your pool, balancing your pool's water chemistry, and then shocking and filtering your pool water. Just be thorough as you clean your pool surfaces. If you leave behind even a small number of algae spores, it won't be long before they regrow and bloom again.
A nylon or rubber brush is the correct choice for scrubbing the sides of a soft-sided above-ground pool. A large pool brush makes quick work of the job, but you may need a smaller brush to clean corners. Once the particles have been removed from the sides of the pool, turn your filter back on and agitate the water.
Pools can immediately turn green after shocking when they have metals like copper in the water. These metals oxidise when exposed to high levels of chlorine which makes the pool water turn green. Adding a metal control product such as Zodiac Metal Remover will help to restore the pool water.
But is it safe to swim in a pool with algae? Whether mild or severe, it isn't recommended. Significant amounts of swimming pool algae welcome a breeding ground of harmful bacteria that feed on algae. These bacteria pose health risks to swimmers, most commonly resulting in a skin rash.
Pool water turns green because of algae in the water. Algae can grow rapidly, particularly when it's warm like Summer, which is why it can surprise you overnight. This generally comes down to an imbalance or lack of chlorine in the water.
A fiberglass pool in its worst condition can be algae-free in 24 hours. For a vinyl liner pool, the process can take 3-4 days. For a concrete pool, this can take a week or more.
However, although the black algae itself won't cause illness, it can attract insects or harbor organisms or harmful bacteria like E. coli, which can make swimmers sick. It's best to avoid swimming in a pool with black algae until you've eradicated it.
Whether you have a vinyl, concrete, or fiberglass pool, it is at its best when it's full of water. Once the water is drained, you open yourself up to all sorts of damage, so drain a pool only when there is no other option. The greatest danger you face when draining a pool is hydrostatic pressure.
Poor water quality, due to an overabundance of Total Dissolved Solids or high levels of Cyanuric Acid, is the most common reason for needing to drain a pool. Even with proper and regular pool maintenance, it's often necessary to drain your pool — completely or partially — every 3-5 years.
Pool industry experts recommend you drain your pool and refill it every five to seven years. No two pools are alike, so there is no set number at which you must drain your pool.
A Rule of Thumb
Generally running your pool pump for 12-hours a day is a good option. This is based on the assumption that your average pool pump has a turnover rate of about 8 to 12-hours. That means that the total volume of your pool water will filter through your system 2 to 3 times per 24-hour period.
So if the pool water isn't cloudy and the 'dirt' is clinging to the walls after brushing, the problem is likely be yellow/mustard algae. Yellow/ Mustard algae is very resistant to even high chlorine levels and will grow and thrive in a chemically well-balanced pool.
Should the green be due to pollen, there may be little to do in the way of minimizing the discoloration short of erecting a building around the pool. Fortunately, assuming there are no allergies to the pollen, it is safe to swim in a pool with that as the cause for green water.
All you need to do is bypass the filter and pool vacuum for algae to the waste. However, this can only work if you have a multiport system or a waste line system in your cartridge filter. Vacuum the pool to waste after you have set up the waste, and the debris and algae will get out of your pool.
When the levels are properly balanced, chlorine will keep the algae at bay, but the water will slowly begin to turn green as the algae take over if there's not enough. But be careful—adding too much chlorine in pool water can cause those metals to oxidize and turn the pool a different shade of green.
Algae growth in your pool will rapidly consume free chlorine. High temperatures, high levels of phosphates, dirty or clogged filters and low chlorine levels can promote algae growth. Scrubbing with a brush can remove algae from surfaces if they have accumulated in one place.
While shocking and adding algaecide is effective in getting rid of algae, it should not be done together. This is because when you mix chlorine and algaecide together, it renders both of them useless. Hence, you should first shock the pool and wait for the chlorine levels to fall below 5 PPM.
ADD POOL CLARIFIER
The change in your pool water colour means that you have successfully eliminated the algae and can now clean it out of your pool. If your water is still green, wait another 24 hours and redo the steps from Days 1 and 2.
The fastest way to clean a green pool is by using pool chemicals and your pool filter. This process usually takes around 4-5 days but you will start noticing a major improvement after 24 hours.