Anyone running two-part dosing on a mid-sized or larger reef learns the same lesson within six months: buying pre-mixed one-liter bottles is quietly bleeding your wallet. The chemistry inside is straightforward — calcium chloride, sodium bicarbonate, magnesium salts — and you're mostly paying for water, plastic, and freight.
Reef Endurance is our answer to that problem, and the full line just arrived at Marine Concept Supply. Pharmaceutical-grade dry powders and bulk filter media, sold in the sizes people actually use — from a couple of pounds for a single tank up to 30 lb bulk buckets for fish rooms and stores.
Two-part dosing chemistry
Everything you need to mix your own alkalinity, calcium, and magnesium solutions:
- Calcium chloride: 2.5 lb or 30 lb pharmaceutical-grade calcium chloride dihydrate.
- Sodium bicarbonate (kH buffer): 4.5 lb or 30 lb for gentle alkalinity dosing.
- Soda ash (sodium carbonate): 3.5 lb or 25 lb for stronger alkalinity correction.
- Magnesium chloride: 3 lb or 30 lb, used with magnesium sulfate for a balanced Mg supplement.
- Magnesium sulfate: 4 lb or 30 lb.
All powders are pharmaceutical-grade and come in resealable 5-gallon buckets at the XL sizes — no more transferring from paper sacks into whatever storage container you can find.
Filter media — activated carbon
Two carbon types, four sizes each, so you can match media to the tank instead of buying whatever bag was on the shelf.
- Aquarium Carbon (virgin coal-based GAC): The general-purpose carbon for removing discoloration, odors, and dissolved organics. Available in 1/4 gal, 1/2 gal, 1 gal, and 5 gal bulk.
- ROX 0.8 Carbon (extruded pellet, acid-washed): The premium option — higher surface area, less dust, and won't crush down in a reactor. Available in 1/4 gal, 1/2 gal, 1 gal, and 5 gal.
Filter media — GFO for phosphate
Granular ferric oxide is still the most reliable way to pull phosphate out of a reef without touching anything else. Reef Endurance GFO comes in four sizes to match reactor volume:
- 1.25 lb (nano/small tank)
- 2.5 lb (mid-size tank)
- 4.5 lb (large tank or extended run)
- 24 lb bulk (multi-tank / fish room / retail)
Calcium reactor media
Aragonite reactor media in two grain sizes, sold as cases of 4 bags for reactors that go through media faster than most people expect:
- Small (fine grain) calcium media — case of 4: For smaller calcium reactors or as secondary post-reactor media.
- Large (coarse grain) calcium media — case of 4: For calcium reactors on larger reef systems.
The math on going bulk
A quick honest note: buying a 30 lb bucket only makes sense if you'll actually use it. Dry powders keep well in a sealed bucket, but a small SPS system dosing modestly might not turn over a 30 lb bag of soda ash in a couple of years. Match the size to your consumption — the smaller bottles are still substantially cheaper per gram than pre-mixed liquid, and there's less to store.
For anyone running multiple tanks, a store, or a heavy SPS build, the XL sizes will pay for themselves inside a few months.
Browse the full Reef Endurance collection, or reach out at shop@marineconceptsupply.com if you want help sizing a two-part system for your tank.
