Aquarium Co-Op Crushed Coral 1 lb

Stock the foundation of a healthy saltwater system or stabilize a freshwater tank that needs higher pH and KH with Aquarium Co-Op Crushed Coral. This 1-pound bag of food-grade calcium carbonate substrate slowly dissolves to buffer your aquarium against pH crashes, keeping water chemistry rock-steady for fish, inverts, and corals. Use it as a base substrate, a pH-boosting top dressing, or dose it into a media bag for filter-driven buffering. Shop more water care & treatments and pair it with our salt mix selection for a full saltwater setup.

Why Hobbyists Choose Crushed Coral

• Stabilizes pH: gradually dissolves to keep pH in the 8.0–8.4 range ideal for reef tanks, African cichlids, and goldfish.
• Boosts KH (carbonate hardness): prevents pH swings during water changes and CO₂ injection.
• Beneficial bacteria substrate: porous calcium carbonate provides huge surface area for nitrifying bacteria.
• Natural aesthetic: looks like authentic reef rubble, perfect for saltwater biotopes.
• Versatile: works as a substrate, sump media, canister media, or HOB buffer.

How to Use

1. As substrate (saltwater): rinse thoroughly under freshwater until the runoff is clear, then layer 1–2 inches across the bottom of the tank. Estimate ~1 lb per gallon for a 1-inch bed.
2. As a pH buffer (freshwater): place 1–2 oz per 10 gallons in a mesh media bag inside a HOB, canister, or sump.
3. For African cichlids / goldfish tanks: mix 25–50% crushed coral with regular sand or gravel to lock in alkaline water chemistry.
4. Maintenance: stir lightly during water changes; replace media bag contents every 6–12 months as the coral dissolves.

Tip: not recommended for South American tetras, discus, or any tank that needs soft, acidic water, crushed coral will push pH and KH higher than those fish prefer.

Specifications

Recommended Pairings

• Salt mixes, for your saltwater setup.
• Water testing kits, monitor pH, KH, and alkalinity as the coral dissolves.
• Calcium & alkalinity supplements, top up trace minerals as needed.
• Filter media, drop crushed coral into a media bag for canister or sump use.

FAQ

Will crushed coral raise my freshwater pH?
Yes, that's the point. It slowly dissolves to push pH into the 7.6–8.4 range, ideal for African cichlids, livebearers, and goldfish. If your fish prefer soft, acidic water, skip the crushed coral.

How long before it stops working?
A 1-pound bag in a media bag for a 30–55 gallon tank typically lasts 6–12 months. As pieces dissolve, KH drops back toward your tap water baseline, that's the signal to top it up.

Do I need to rinse it before adding to my tank?
Always. Rinse thoroughly with freshwater (no soap, no chemicals) until the runoff is clear before placing it in your tank or filter.

Can I use it in a planted tank?
Only if you're not running CO₂ injection. Crushed coral fights the slight pH drop that CO₂ creates, which works against planted-tank chemistry.