Rid pool of black spot and mustard algae

Usually Pool Crystals will kill and control black spot and mustard algae with a normal application. However, if it is a long-standing problem and well established in a pool, it will need a different approach and some initial extra help.

To do this the pool should be “shocked” with a high dose of chlorine to bring it up to approximately 10 ppm.

First, temporarily lower the pH to 6.8 by using hydrochloric acid. This is because the efficiency and consequent effectiveness of chlorine is directly related to the pH. The “killing power” of chlorine lessens rapidly as the pH level rises.

The high dosage of chlorine combined with the Pool Crystals treatment will burn out the black spot and mustard and any other algae and also destroy excessive chloramines.

First, temporarily lower the pH to 6.8 by using hydrochloric acid. This is because the efficiency and consequent effectiveness of chlorine is directly related to the pH. The “killing power” of chlorine lessens rapidly as the pH level rises.

The high dosage of chlorine combined with the Pool Crystals treatment will burn out the black spot and mustard any other algae and also destroy excessive chloramines.

In a couple of days the black spot and mustard algae should become softer and turn a sticky brown. Because black spot and mustard algae spores are particularly tenacious and usually adhere strongly to pool surfaces, it will most likely need to be brushed down to loosen its grip. The dead algae will then be oxidised out by the chlorine in the water. Because this oxidation process is taking place disposing of dead algae residue, the chlorine level will drop rapidly as it is consumed.

With the Black Spot problem resolved…

The filter should be backwashed to remove any residual debris. The Total Alkalinity and pH of the pool water should be re-established at the correct level for your particular pool surface and the chlorine level should be topped up as necessary to maintain it at 1.5 ppm or to 2.0 ppm if the water temperature is above 26 degrees Celcius. Thereafter, regular normal applications of Pool Crystals should prevent blackspot and mustard algae from reoccurring.