A reef tank dosing supplement is simply a chemical solution that you add to your tank to replace those used by your corals and invertebrates.
The chemical elements of Carbonate (Alkalinity), Calcium and Magnesium are the main ones used by corals as they grow.
Regular testing will establish which elements are being used up and by how much. We look now at what supplements to use to replace them.
Table of Contents
Top 5 Reef Tank Dosing Supplements
| # | Preview | Product | Quick Review |
| 1 |  | Aquaforest Reef Tank Supplements | Best For Dosing |
| 2 |  | Seachem Reef Tank Supplements | Good Products |
| 3 |  | Salifert All In One | Lacks Flexibility |
| 4 |  | Continuum Aquatics Reef-Basis Supplements | Expensive |
| 5 |  | Brightwell Aquatics Alkalin8.3-PH | KH Buffer Only |
Why You Should Use Reef Tank Supplements
As your coral reef tank matures and your corals begin to grow, the key chemical elements of Carbonate (Alkalinity), Calcium and Magnesium will slowly deplete.
A percentage water change will not fully replace them so we need to give them a boost by adding them back to the water.
It’s perfectly possible to mix your own reef tank supplements but the recipes can be tricky and most reefers don’t want the hassle so buy off the shelf.
What to Look for When Buying a Reef Tank Supplement
Simplicity and Ease of Use – We think the most important thing to look for is simplicity and ease of use.
The liquid solutions are the easiest, but if it’s just a matter of mixing a set amount of powder or crystals in RO water to make your own solution, then that’s also fine.
Easy to Follow Formula – you need to know how much of the supplement to add to get the desired increase in your target parameter.
Reef Tank Supplements Product Reviews
Here are my reviews of the best reef tank supplement products:-
1. Aquaforest Reef Tank Supplements
The Aquaforest Reef Tank Supplements range covers the main elements of Alkalinity(KH), Calcium and Magnesium. Easy to use and ideal for automated dosing using a good reef tank dosing pump.
1. KH Buffer
- Maintains carbonate hardness in a reef tank. Contains NaHCO3.
- Mix 80g of the product in 1 litre of RO water for dosing.
- 10g increases by about 3.3 dKH.
- Use in conjunction with Aquaforest Calcium and Magnesium.
2. Calcium
- Maintains calcium level in a reef tank.
- Mix 50g of the product and 10g of Magnesium Aquaforest in 1 litre of RO water for dosing.
- 10g in 100l of water increases by about 35 mg/l (ppm ) calcium levels.
- Use in conjunction with Aquaforest KH Buffer
3. Magnesium
- Maintains magnesium levels in a reef tank. Contains MgCl2.
- Mix 10g of the product and 50g of Calcium Aquaforest in 1 litre of RO water for dosing.
- 10g in 100l of water increases by about 12mg /l (ppm ) levels of magnesium.
- Use in conjunction with Aquaforest KH Buffer.
Pros
- Great For Automated Dosing
- Great Value
- Easy To Use
- Mixes Well
Cons
- None
2. Seachem Reef Tank Supplements
The Seachem Reef Tank Supplements range is one of the most extensive on the market. As well as covering the main elements of Alkalinity (KH), Calcium and Magnesium, they also have products for Iodide, Strontium and Trace Elements.
They have a number of different products for dosing for Calcium and Carbonate(KH):-
Reef Calcium / Reef Carbonate (KH) – To be used separately to raise Calcium and Carbonate(KH). Use if one or the other is out of balance.
Reef Fusion – Is a two-part dosing solution where both Calcium and Carbonate(KH) are added together in a 1:1 ratio. Use when Calcium and Carbonate(KH) are in balance.
Reef Complete – is a liquid ionic calcium source that also includes magnesium and strontium.
Reef Advantage Calcium – as Reef Complete but in powder form which is easily dissolved in RO water for dosing.
For Magnesium dosing:-
Reef Advantage Magnesium – is a blended, ionically balanced magnesium source containing NO Ammonia. Comes as crystals that are easily dissolved in RO water for dosing.
Pros
- Extensive Product Range
- Easy To Use
- Online Dosing Calculator
Cons
- Confusing Product Range
- Relatively Expensive
3. Salifert All In One
Salifert All In One is a combined calcium and alkalinity supplement that claims to increase the carbonate hardness, calcium, strontium, trace elements and amino acids concentrations.
Their KH pH buffer is also recommended to compensate for alkalinity lost which is a little confusing.
No mention of magnesium, though Salifert does sell a separate Magnesium supplement.
We’ve never used an All In One so we can’t really comment but it may be worth a try in a small Nano reef tank.
Pros
- All In One
- Cheap
- Maybe OK for Nano Tanks
Cons
- All In One
- Lacks Flexibility and Control of Dosing Separately
4. Continuum Aquatics Reef-Basis Supplements
Continuum Aquatics provide supplements covering Alkalinity (KH), Calcium and Magnesium, and also for Iodide, Strontium and coral feeding.
Available in liquid or powder formats.
Pros
- Easy to use
- Liquid or powder
Cons
- Expensive
5. Brightwell Aquatics Alkalin8.3-PH
Brightwell Aquatics KH pH buffer does what it ways on the tin.
However, you will need more than just a KH Buffer for a stable reef tank.
Pros
- Does the job
Cons
- Cheaper options available
Conclusion
The Aquaforest Reef Tank Supplements range gets our vote as they are easy to use, inexpensive and come with clear dosing formulas.
The Seachem range of products is good, no question but the range has become too complicated. How many different calcium supplements do you need? We think ONE will suffice.
Remember, the easiest way to dose your reef tank is to automate the process using a good reef tank dosing pump.
Reef Tank Supplements FAQs
What should I be dosing in my marine tank? – You will only need to dose if you keep corals. Corals utilise calcium, carbonate and magnesium to grow so these will deplete over time in your tank water. We add them back by dosing supplements.
Do you need supplements for a reef tank? – Yes, as the corals in your reef tank grow they will deplete the amount of calcium, carbonate and magnesium in the water. Dosing supplements will keep the amount of those elements up to the optimum level.
When should I start dosing my reef tank? – As soon as you start to add corals you should regularly test the levels of calcium, carbonate and magnesium in the water. When these levels start to drop you should start dosing.
Is there a DIY Reef Tank Supplements Recipe? – Yes. For example, you can use Baking Soda mixed with RO water as a carbonate supplement or Calcium Chloride as a calcium supplement. Recipes are available online or check out our own, DIY Two Part Dosing Recipe.
How much of each supplement should I add? – Carefully follow the instructions that come with the supplement. Go slowly. Add, maybe half the recommended amount and go from there, testing regularly as you do so.
What is 2 Part dosing for a reef tank? – 2 part dosing for a reef tank refers to the replacement of calcium and carbonate in the water that is used by growing corals. Solutions of each are added back in equal amounts.
What happens if I accidentally dose too much? – Go slowly, with a lower dose at first. If you do overshoot, simply stop dosing that supplement until test results return to acceptable levels. If you really add far too much, do a water change.