Red Sea Salt 25.2kg bag (750L)
Cost per litre
$0.24
Water type
Marine + Reef
Red Sea Salt 25.2kg bag (750L)
One 25.2 kg bag mixes 750 litres of moderate-alkalinity reef seawater. Red Sea Salt is Red Sea's original marine salt mix, formulated to a natural, reef-stable alkalinity that suits fish-only systems and reef tanks run without heavy supplementation. This is the largest of the three Red Sea Salt pack sizes we stock.
Key features
- Makes 750 litres — one 25.2 kg bag mixed to reef salinity (35 ppt), roughly fifteen 50 L water changes.
- Moderate, reef-stable alkalinity — 7.7–8.1 dKH at 35 ppt, closer to natural seawater than the elevated alkalinity of Coral Pro Salt.
- Dissolves fast and clean, with no cloudy residue once fully circulated.
- One bag, fewer deliveries — suited to larger systems or shop tanks doing frequent water changes.
Specifications
| Pack weight | 25.2 kg |
|---|---|
| Makes | 750 L at reef salinity (35 ppt) |
| Alkalinity at 35 ppt | 7.7–8.1 dKH |
| Calcium at 35 ppt | 415–430 mg/L |
| Magnesium at 35 ppt | 1,230–1,290 mg/L |
| Potassium at 35 ppt | 375–395 mg/L |
| Format | Bag — decant into a sealed container |
Which pack size do I need?
We stock Red Sea Salt in three pack sizes. Cost per litre doesn't scale with pack size the way you'd expect, so it's worth checking the numbers rather than assuming bigger is cheaper:
| Pack | Makes |
|---|---|
| 10 kg bag | 300 L |
| 25.2 kg bag (this listing) | 750 L |
| 20 kg refill box | 600 L |
At 750 L per bag, this size suits larger systems and shops that want fewer, bigger deliveries rather than the lowest cost per litre — the 10 kg bag is cheaper litre for litre, but means buying more often.
Dosage and directions
Mix into clean RO or RO/DI water with circulation until fully dissolved — allow around 20 minutes. Aerate before use, and match temperature and salinity to your display before adding. Mix in batches rather than all at once if your container can't hold the full 750 L.
Suitable for, and not suitable for
Suited to fish-only systems and reef tanks running natural or lightly dosed nutrient levels, and to larger displays or shop systems where buying in bulk cuts down on repeat orders. Reef tanks with heavy calcium and alkalinity demand from fast SPS growth are usually better matched to Red Sea's Coral Pro Salt, which mixes to a higher starting alkalinity and calcium level.
Care and maintenance
Store sealed and dry, off the floor. Reseal the bag firmly between uses — moisture reaching the unmixed salt changes the effective mix ratio for later batches.
Warranty and delivery
Sold subject to Red Sea's standard product guarantees, which apply in addition to your consumer guarantee rights under Australian Consumer Law. Ships as a single carton — no special freight handling required.
Common questions
Is the 25.2 kg bag better value than the smaller bag?
Litre for litre, no — compare the current cost per litre for each pack size on the product page before deciding. This size is aimed at larger systems and shops wanting fewer, bigger deliveries rather than the lowest cost per litre.
Does the bag include a measuring scoop?
No — pair it with our Red Sea Salt Measuring Cup for consistent, repeatable dosing.
What's the difference between this and Coral Pro Salt?
Red Sea Salt mixes to a moderate alkalinity, around 8 dKH, suited to fish-only tanks and naturally-run reefs. Coral Pro Salt mixes to a higher starting alkalinity and calcium level for reef tanks with heavier coral growth demand.
How is a 25.2 kg bag best stored?
Sealed and dry, off the floor. Once opened, reseal firmly between uses.
