Member's Mark Algaecide 40

Member's Mark™ Algaecide 40 helps treat and control algae and algae slime in pool and spa water, with labeled dosing guidance for both initial treatment and ongoing maintenance.

Broad-use algae treatment for pools and spas

Suitable for swimming pools, spas, whirlpools, and hot tub baths, this algaecide targets a wide range of algae. It is specifically effective against Chlorella pyrenoidosa (green algae) and Phormidium, which can contribute to visible algae growth and slime in pool water.

Warm-water performance

Member's Mark Algaecide 40 becomes more effective as pool water temperatures rise, supporting algae control during warmer months.

Clear dosing guidance for startup and maintenance

• Initial dosage: Add 3.2 oz per 5,000 gal.
• Maintenance dosage: Add 0.8 oz per 5,000 gal.
• Maintenance frequency: Add the maintenance dose at 3–5 day intervals.
• This listing includes a set of two, giving you extra supply on hand for routine dosing and continued algae treatment.

Formula details and compatibility notes

• Active ingredient: Alkyl (50% C14, 40% C12, 10% C16) dimethyl benzyl ammonium chloride.
• pH range: 6.0–8.0.
• Solubility: Completely soluble.
• Compatibility: Incompatible with anionic surfactants.
• Shelf life: 2 years.

Important safety information

Warning: Corrosive. Causes irreversible eye damage and skin burns. Harmful if inhaled. Keep out of reach of children.

Frequently Asked Questions

Can I use Member's Mark Algaecide 40 in both a swimming pool and a hot tub?

It’s intended for swimming pools, spas, whirlpools, and hot tub baths.

What does Member's Mark Algaecide 40 help control?

It’s designed to control the growth of algae and algae slime in swimming pools.

What types of algae is Member's Mark Algaecide 40 effective against?

It’s particularly effective against Chlorella pyrenoidosa (green algae) and Phormidium.

Does Member's Mark Algaecide 40 work better in warm water?

Its effectiveness increases as pool water temperatures rise.

What is the active ingredient in Member's Mark Algaecide 40?

Alkyl (50% C14, 40% C12, 10% C16) dimethyl benzyl ammonium chloride.

Is Member's Mark Algaecide 40 soluble in water?

It is completely soluble.

Are there any compatibility restrictions for Member's Mark Algaecide 40?

It is incompatible with anionic surfactants.

What safety warnings are listed for Member's Mark Algaecide 40?

Corrosive; causes irreversible eye damage and skin burns; harmful if inhaled; keep out of reach of children.

What is the shelf life of Member's Mark Algaecide 40?

Shelf life is 2 years.

Does Member's Mark Algaecide 40 come as a multi-pack?

It comes in a set of two.