✓ The Science

Cyanoacrylate polymerizes (hardens) when exposed to water. Saltwater accelerates this process. Once cured, CA glue becomes an inert plastic polymer that will not leach anything into your reef tank. It's been used safely in reef aquariums for over 20 years.

⚠️ Important Caveats

• Uncured CA releases heat — When CA hits water, the curing reaction is exothermic. Applying too much CA directly on coral tissue can burn it. Always apply to the plug/rock first, not the coral.
• Gel viscosity is crucial — Thin CA can flow before it cures, potentially reaching fish gills or coral mouths. Use thick, gel-consistency CA for underwater work.
• White residue is normal — CA sometimes leaves a white "bloom" as it cures in saltwater. This is harmless and can be scrubbed off or left to dissolve naturally.

Step-by-Step:

1. Dab Thick CA Gel on the frag plug — Use a gel-consistency CA (1500 CPS or thicker). Apply a small ball, about pea-sized. Don't go crazy—excess glue just strings through your tank.
2. Add a ball of two-part epoxy on top of the CA — Mix epoxy to the consistency of putty. Place it on the CA glue. This creates a mechanical barrier and fills uneven surfaces.
3. Add another drop of gel CA on top of the epoxy — This "sandwiches" the epoxy between two CA layers.
4. Press the frag firmly onto the rock — Use a slight twisting motion to work the glue/epoxy into the rock's pores. Hold steady for 15-30 seconds.
5. Check the bond after 30 seconds — Give it a gentle tug. If it moves, add more CA around the base and hold again.

💡 Why This Works

The CA provides instant tack, the epoxy fills gaps and creates surface area, and the second CA layer bonds the coral to the epoxy. You get immediate hold plus long-term strength. This method works even on wet, porous rock where CA alone might fail.

The Technique:

1. Remove the rock to a tray with high walls — Catch the dripping water. Work fast to minimize stress on the coral.
2. Pat the bonding spot dry with a paper towel — You want it as dry as possible. This lets the CA bond chemically instead of just polymerizing on contact with water.
3. Apply Thick CA Gel to both the plug and the rock — A thin layer on each surface creates maximum bonding.
4. Press together and hold for 20 seconds — Twist slightly to spread the glue. You'll feel it tack almost immediately.
5. Return the rock to the tank — The bond is strong enough to handle. Water contact will finish the cure.

⚡ Pro Tip: Keep Frags Submerged During Prep

While you want the bonding surface dry, keep the coral itself wet. Fill a shallow dish with tank water and keep frags submerged until you're ready to glue. Coral tissue can desiccate in seconds in dry air.

Special Case: CA Glue Gel Products

Many reef supply companies sell "coral glue" which is just thick CA gel in small tubes. These work great but are expensive per ounce. Industrial-grade Thick CA (1500 CPS) from Glue Masters is the same chemistry at a fraction of the cost.

Pro reefers buy bulk and refill small applicator bottles. A 16oz bottle of Thick CA will frag hundreds of corals.

Bonding Large Rocks Together:

1. Dry fit your rocks out of the tank — Figure out your structure first. Mark contact points with a crayon.
2. Apply Thick CA Gel to contact surfaces — Use enough to fill small gaps but not so much it drips.
3. Press rocks together firmly for 30 seconds — The CA will tack, holding them in position.
4. Reinforce joints with two-part epoxy — While the CA holds the rocks, mix epoxy and apply around joints. This adds structural strength.
5. Add another bead of CA over the epoxy — This speeds the cure and creates a hybrid bond that's both instant and durable.

When two rocks sit tightly together but aren't quite bonded, you can wick Ultra Thin CA into the joint:

• Hold rocks firmly in position (have a helper or use clamps)
• Apply Ultra Thin CA at the top of the joint seam
• Watch it wick down into the crack by capillary action
• The ultra-low viscosity penetrates deep, bonding the entire joint from inside
• Give it 60 seconds to cure before releasing pressure

This is an advanced technique but creates incredibly strong bonds because the CA penetrates the porous rock structure.

💡 Universal Rule: Glue the Base, Not the Tissue

Always apply CA to the frag plug, rubble, or skeleton—never directly to living coral tissue. The exothermic curing reaction can burn flesh. Let the coral attach naturally to the cured glue.

❌ Using Too Much Glue

Excess CA creates strings, wastes product, and can trap air bubbles under the frag. Use pea-sized amounts. You can always add more.

❌ Mounting Wet Frags on Wet Surfaces with Thin CA

Thin CA + water = instant polymerization before bonding occurs. Result: glue everywhere, no bond. Use Thick CA Gel for underwater work.

❌ Not Holding Long Enough

Even gel CA needs 20-30 seconds of firm pressure to bond properly underwater. Letting go too soon = frag falls off in an hour.

❌ Gluing Directly to Glass or Acrylic

CA bonds so well to glass that removing frags later can crack the tank. Always use a plug or rubble piece as an intermediary.

Thick CA Gel (1500 CPS)

Gel consistency for underwater frag mounting

16 oz Bottle

Ultra Thin CA (05 CPS)

For wicking into rock joints during aquascaping

16 oz Bottle

CA Glue Gel (20g)

Convenient small tube for spot fragging

20g Tube

2-Part Epoxy

For the gel sandwich method and aquascaping

5-Minute Set

Frag Mounting

Thick CA Gel (1500 CPS)
Gel sandwich method
Hold 20-30 seconds

Aquascaping Rocks

Thick CA + 2-part epoxy
Ultra Thin for wicking joints
Dry fit first

Best Practices

Glue the base, not tissue
Use pea-sized amounts
Keep frags submerged

Safety

Reef-safe after full cure
Avoid excessive heat
White bloom is normal