Brightwell ChaetoGro — nitrogen- and phosphorus-free refugium fertilizer for chaetomorpha

The Brightwell ChaetoGro is a targeted fertilizer for chaetomorpha and refugium macroalgae in marine and ULNS reef systems. Formulated in the United States by Brightwell Aquatics, it delivers 13 elements essential to aquatic plant growth — without nitrogen (N) or phosphorus (P), which would run counter to the export role the algae already plays.

How do you grow chaetomorpha in a refugium? Strong lighting run 24/7 or on a reverse cycle to the display, enough flow to tumble the algae ball and expose every face to light, and a supplement of iron, potassium, and trace elements when the tank runs ULNS — the exact role ChaetoGro fills. The product is shrimp and invertebrate safe.

What ChaetoGro is for and when to use it

Refugium on a ULNS tank — chaetomorpha that plateaus because NO₃ and PO₄ are too low to keep growing; ChaetoGro supplies micronutrients without restarting the nutrient spiral.
Starting a new refugium — the first 2 weeks to establish algae ball growth.
Iron and potassium reinforcement — tanks where ICP flags an Fe, K, Mn, or Mo deficit hurting macroalgae photosynthesis.
Outcompeting nuisance algae — feeding chaetomorpha to make it more competitive against cyanobacteria and turf algae on the display tank.

Brightwell official dosing

Basic dose (weekly): for the first 2 weeks, 5 mL (1 capful) per 20 US gal (76 L) of aquarium volume, twice a week. Adjust afterwards based on the chaeto's perceived nutrient needs.
Alternative dose (daily): 6 drops per 20 US gal per day. Adjust after a week based on algae appearance and nutrient need.
A 500 mL bottle treats up to 2,000 US gal (7,600 L) on the basic weekly ratio.

Brightwell official composition

ChaetoGro delivers 13 elements critical to long-term aquatic plant health: potassium, boron, carbon, calcium, chlorine, iron, magnesium, manganese, molybdenum, cobalt, nickel, sulfur, and zinc. The product contains neither phosphorus nor nitrogen — macroalgae pull those macronutrients directly from the display tank water.

Guaranteed analysis: N-P-K 0-0-1.30 % (potassium), iron 0.1 %, magnesium 0.4 %, manganese 0.0475 %.

Specifications

Brand: Brightwell Aquatics (made in the USA)
Available sizes: 250 mL, 500 mL
Type: refugium fertilizer without N or P
Safe for: shrimp and invertebrates (Brightwell: "Shrimp & Invertebrate safe")
Target: chaetomorpha and refugium macroalgae in marine systems, including ULNS

Why choose Brightwell at ReefSolution

Brightwell MicroBacter7 — the bioculture to maintain display-tank biology while the refugium exports nutrients.
Brightwell NeoNitro — the nitrate booster to balance against ChaetoGro if ULNS has starved the chaeto.
Brightwell NeoPhos — the phosphate booster to pair with NeoNitro and restart growth on a healthy Redfield ratio.

Frequently asked questions

How do you grow chaetomorpha in a refugium?

Three conditions per Brightwell's documentation and reef practice: strong lighting (broad spectrum, often run 24/7 on a reverse cycle), enough flow to tumble the algae ball and expose all faces to light, and delivery of the 13 micronutrients ChaetoGro supplies. The Brightwell weekly ratio (5 mL per 20 US gal, twice a week) is the baseline; adjust after 2 weeks based on observed growth speed.

Does ChaetoGro contain phosphate or nitrate?

No — Brightwell states that ChaetoGro contains neither phosphorus (P) nor nitrogen (N). Those are the only macronutrients chaetomorpha still pulls from the display tank water — ChaetoGro delivers all the rest (K, Fe, Mg, Mn, Mo, Co, Ni, S, Zn, B, Ca, Cl, C).

Can ChaetoGro be dosed on a reef tank without a refugium?

The product is formulated for a refugium or a marine system hosting macroalgae. Without a plant to feed, the 13 elements risk being consumed by nuisance algae or getting out of balance. Brightwell positions ChaetoGro specifically for chaeto and macroalgae cultivation, not as a general reef additive.

How long does a 500 mL ChaetoGro bottle last?

Brightwell states 2,000 US gal (7,600 L) treated per 500 mL bottle on the basic weekly ratio. On a 25 US gal refugium under daily dosing (6 drops per 20 US gal), the practical duration comfortably exceeds one year.