Bleach Experiment

Why is this research important?

Maintaining a pool is expensive and there are many different opinions about which chemicals remove the most algae from the water. Some people believe that household bleach works just as well as a shock treatment such as the expensive hypochlorites, and it helps save people a lot of money each year on pool maintenance. This experiment will discover if this popular idea is true by measuring how effective bleach is in removing algae and comparing the results with expensive store-bought shock treatments.

The Problem

Which chemical [bleach (containing sodium hypochlorite 6%), Chlor Brite (containing sodium dichloro-s-triazinetrione dihydrate), Power Powder Plus Shock (containing calcium hypochlorite), and

The Procedure

Independent: regular bleach (containing sodium hypochlorite 8.25%)

Chlor Brite (containing sodium dichloro-s-triazinetrione dihydrate)

Power Powder Plus Shock (containing calcium hypochlorite)

Crystal Shock (containing lithium hypochlorite)

Dependent: algae concentration

Controls: (Should include at least 5 controls)

Treatment schedule: each sample will receive the same number of treatments of each chemical

Treatment concentration: each sample will receive the same quantity of each chemical at each treatment

Location: all samples will sit on the same windowsill inside home, so they get sunlight but do not get rained on.

Sample size: each sample will be 250 mL

Sample source: each sample will use the same source of algae

These containers will be divided into 5 groups: a tap water control group, an algae water control group (3 samples), a household bleach group (3 samples), a Chlor Brite group (3 samples), a Power Powder Plus Shock group (3 samples), a Crystal Shock group (3 samples). Chemicals will be added every 3 days and algae growth will be documented every 3 days, as explained in the procedure below:

1: Collect 3 gallons of algae-filled water from grandparent’s pool.

2: Collect 1 gallon of tap water from the water hose outside home.

3: Prepare a dilution of the 3 chemical powders (Chlor Brite, Powder Plus Shock, Crystal Shock) and the bleach. The preparation of the dilutions is a multi-step process in which the dilution is appropriate for a 250 ml sample of algae water. Chlor Brite:

Dissolve 8 grams of the powder into 4 liters of tap water

Remove 1 ml of this solution

Add this to 1 liter of water

Remove 1 ml of this solution to add to samples in the D group Power Powder Plus