It important to reduce the amount of potential pathogens in the aquarium as much as is practical. To protect the eggs and fish against disease causing bacteria and fungus, the aquarium and other related equipment that will be touching the aquarium water will need to be cleaned. This includes any thermometers, pumps, filters.
1. Rinse dirt off of aquarium, related equipment and rocks.
Clean as much dirt and organic matter off of it as possible with plain water. Do not use soap or other chemicals. Organic "dirt" such as fish poop and rotting fish food can drastically reduce the germicidal effectiveness of the bleach you will use on the equipment.
2. Boil gravel and rocks in plain water at a rolling boil for 10-20 minutes. Dry them completely before they are stored.
The rocks will not need to be treated with bleach. Instead, the rocks should be boiled to avoid introducing any parasites, fungus, or bacteria to the aquarium from the rocks and gravel you will be using. Boiling the rocks and gravel for 10-20 minutes In regular tap water that is at a rolling boll should kill any unwanted pathogens.
CAUTION-rocks stay hot for a very long time. Let them cool a long time before you handle them . Spread them on a clean surface in the sun to finish drying.
3. Make the bleach solution.
Sodium hypochlorite is the active ingredient in household or chlorine bleach. Bleach is a solution of sodium, hypochlorite (NaOCI) and water. In 2012, some manufacturers, including the Clorox Company, increased their bleach formula to a strength of 8.25% from the former 5.25%. Most "regular" bleach available in the U.S. today is 8.25% sodium hypochlorite. Some bleach that is sold commercially as a janitorial supply, Is 6.15% sodium hypochlorite. Thickened or "splashless" bleach has only 1-5% sodium hypochlorite. Scented bleaches may also have lower sodium hypochlorite content. Many types of bleach do not state a percentage on the label.
Read the label on the bleach bottle. It should list the percentage of sodium hypochlorite.
The concentration of the bleach solution to be used on the aquarium equipment
It is recommended to use a chlorine bleach solution of 200mg/L for fish tanks and the equipment. To obtain a solution of that strength; use only plain, unscented, regular, bleach with water in the quantities in the table below.
Water Bleach Strength = 8.25% sodium hypochlorite Bleach Strength = 5.25·6.25% sodium hypochlorite
1 quart 1/2 tsp 1 tsp
1 gallon 2 tsps 4 tsps
The temperature of the bleach solution
The hotter the bleach solution, the more active the chlorine will be against pathogens. Although 120°F is a recommended temperature for the bleach solution, it is very warm and can be uncomfortable to work in, so use the warmest water you can comfortably work with.
The duration of exposure of the equipment to the bleach solution
It is recommended that the chlorine bleach solution be in contact with the aquarium and equipment for one hour.
The bleach solution is very toxic to fish and should be rinsed off very thoroughly before using the equipment with the fish.