• HDPE containers work well — we also sell HDPE jugs.
• Glass containers
• Don't use acrylic containers, including but not limited to the Neptune DDR – DŌS Dual Reservoir. Sodium hydroxide attacks acrylic — the seams will fail and leak all over the floor.

We recommend:

• LLDPE tubing (standard RO/DI tubing)
• PharMed BPT tubing
• Clear PVC tubing (Neptune DOS dosing lines)
• Silicone tubing will only last 5–8 months before failing.

Using other tubing materials to dose the sodium-hydroxide-based alkalinity solution (Part 1B) can result in melted tubing and contaminated tank water.

Most of the time, a big drop or increase like this is the test kit's margin of error. Popular kits like the Hanna calcium checker, Salifert calcium/magnesium kits, and the Neptune Trident are great for watching trends — but they are not precise enough to drive dosing changes.

But DO NOT adjust your calcium/magnesium dosage based on those results alone. Always check alkalinity first — most alkalinity test kits are far more accurate than calcium checkers. For a reliable check of calcium and magnesium, we recommend an ICP-OES or ICP-MS test every 3–4 months.

If you are still stressed out, let's do a sanity check:

For every 1 meq/L (2.8 dKH) of alkalinity, calcification consumes 20 ppm calcium. Magnesium follows in a much smaller amount — up to about 0.06 ppm Mg per 1 ppm Ca in coralline-heavy tanks (high-magnesium calcite), and far less (~0.005) in the aragonite that corals deposit. Check your own numbers with the calculators below.

So a 50 ppm drop in calcium would require a 7 dKH drop in alkalinity — and just 3 ppm of magnesium. If your alkalinity hasn't fallen 7 dKH over those same few days, the calcium reading is the problem.

It almost never is. This is the most common question we get, and the answer is the same in nearly every case: the calcium/magnesium test is off, not the tank.

Calcification is a single chemical reaction. Corals, coralline algae, clams, and every other calcifying organism deposit calcium carbonate (CaCO₃), and that mineral has a fixed makeup. Calcification can therefore only consume calcium and alkalinity together, at a locked ratio:

• 20 ppm calcium per 2.8 dKH (1 meq/L) of alkalinity — about 7.1 ppm Ca per 1 dKH.
• Magnesium substitutes into the skeleton in tiny amounts — about 0.06 ppm Mg per 1 ppm Ca in high-magnesium calcite (coralline algae), and far less (~0.005) in the aragonite corals deposit.

To be clear: a reef tank does have alkalinity consumers that are not calcifying organisms — nitrification in the nitrogen cycle and local precipitation both spend alkalinity with little or no calcium demand. We take those into account: our NAF 2-Part (V5) Part 1 is built with a deliberate ≈1.5–2% extra alkalinity per unit calcium, so the 1:1 dose covers those extra sinks along with calcification.

The recipe: Part 1 is the alkalinity side — sodium hydroxide (alkalinity + pH) with sodium fluoride, borate, and trace salts — concentrated to ≈6,920 dKH. Part 2 is the calcium/magnesium side — calcium chloride, magnesium salts, and trace elements — concentrated to ≈48,700 ppm calcium and ≈4,870 ppm magnesium. Dosed 1:1, they deliver ≈7.0 ppm Ca per 1 dKH — slightly less than the ≈7.15 ppm Ca per dKH that calcification alone removes, and that gap is the headroom we designed in.

But those extra sinks are small — a fraction of a dKH per day in a healthy tank. If your alkalinity is dropping by a full dKH or more per day while your calcium test doesn't budge, the mismatch is still a test-kit artifact. Hobby calcium and magnesium kits (Hanna checker, Salifert, Trident, etc.) are far less precise than alkalinity kits — a calcium reading can swing 20–40 ppm between runs, which is exactly the size of the imbalance people see. Trust the alkalinity number, keep dosing both parts equally, and confirm Ca/Mg with an ICP test every few months.

We know it's a hard pill to swallow — it's genuinely frustrating that the hobby Ca/Mg tests aren't trustworthy enough to fine-tune against. But the chemistry doesn't leave much room: if your tank is burning 1 dKH/day, it is using ~7 ppm calcium/day with it, whether or not your test kit shows it.

No — a jump that size is a test error, and it is easy to prove with the math.

NAF 2-Part (V5) Part 2 is concentrated to ≈4,870 ppm magnesium. One milliliter added to a 100-gallon system raises magnesium by only ≈0.013 ppm. So even a generous 50 mL/day dose adds roughly 0.6 ppm Mg per day — before your corals and coralline remove any.

A genuine 70 ppm rise would require about 5,400 mL (nearly 1.5 gallons) of Part 2 in a 100-gallon tank. If you are not pouring in gallons of it, the number on the kit is wrong. The same logic applies to calcium: Part 2 is ≈48,700 ppm Ca, so 1 mL in 100 gallons is ≈0.13 ppm Ca.

Calcium and magnesium are major ions that can only move a few ppm per day from normal dosing. A double-digit swing over a few days is a measurement artifact — test drift, old reagent, a dirty cuvette, or an off titration — not your dosing. Re-test, or compare against an ICP result, before changing anything.

Over weeks and months, a slow drift of several ppm per month can be real — your Part 2 adds a little more magnesium than a typical tank's skeletons take up. That is expected, and it's what your quarterly ICP check is for. A double-digit swing in a few days, though, is the kit.

Work backward from alkalinity — it is the one hobby test you can trust. For every 1 dKH of alkalinity your tank consumes, calcification removes ≈7.1 ppm calcium (plus a little alkalinity for the nitrogen cycle and precipitation, which our Part 1 already covers). Magnesium follows at a much smaller ratio: ≈0.06 ppm Mg per 1 ppm Ca in a coralline-heavy tank (high-Mg calcite), and ≈0.005 in pure coral aragonite.

• 1 dKH/day consumed → ≈7.1 ppm Ca/day and ≈0.4 ppm Mg/day (coralline-heavy) removed.
• A 50 ppm calcium drop without a matching ≈7 dKH alkalinity drop is physically impossible.

Use the Two-Part Sanity Calculators below to check your own numbers: enter your daily alkalinity dose and compare the predicted Ca/Mg consumption against what your tests claim. If they disagree by more than the kit's typical error (often ±20–40 ppm Ca and ±30–60 ppm Mg), it is the kit.

Our NAF 2-Part Part 1 is sodium-hydroxide-based, so every dose consumes dissolved CO₂ and lifts pH — carbonate and bicarbonate products can't do that, which is why soda ash gives almost no pH lift.

• Most tanks see about +0.2 pH. (Honest limit: if the room air is high in CO₂, no dosing product can fully override the atmosphere — test by aerating a cup of tank water outside for an hour, and fix the air first.)
• Cost, for a 100-gallon tank burning 1 dKH/day: NAF 2-Part ≈ $0.65/day (raises pH while dosing calcium, alkalinity, and traces); a CO₂ scrubber ≈ $10–20/month in media alone, pH-only; kalkwasser is pennies but capped at your evaporation rate and needs an ATO.

See the product page's pH section for the full chemistry.

Unfortunately no. The calcium/magnesium concentration in NAF 2-Part is specifically designed to match coral alkalinity consumption, not to correct low levels. You would need a LOT of Part 2 to raise a low calcium/magnesium level — which is not cost efficient.

• First, check whether your salt mix is low in calcium (< 400 ppm) or magnesium (< 1,350 ppm).
• To raise calcium or magnesium to your target, use NAF - Calcium or NAF - Magnesium.

We strongly recommend you always dose Part 1 and Part 2 together at a 1 ml : 1 ml ratio (5–15 minutes apart), because we designed the 2-Part as a system to support coral growth.

• Dosing only Part 1 or Part 2 will throw the elemental balance off, which can ultimately cause coral health to decline or even bleach.
• Part 2 also plays a big role in boosting coral growth. One customer told us he was dosing only Part 1 because his calcium and magnesium were very high from an all-in-one product he had used before. After a while his calcium dropped back to normal, so he started dosing Part 2 as well — and he noticed a much bigger alkalinity consumption than before. The trace elements in Part 2 (the minor and organic salts) had pushed his corals to grow faster.

We include a large amount of fluoride and a decent amount of iodide in our Part 1B. However, most salt mixes on the market are deficient in fluoride, manganese, and magnesium (all expensive to add), so it is very difficult to use NAF 2-Part to raise the fluoride level of the whole tank back to the ideal range if your salt is deficient.

To raise fluoride, we recommend dosing NAF - Fluoride in addition. For iodide, use NAF - Iodide.

The white paste is most likely magnesium hydroxide (and some calcium carbonate) precipitation, caused by a sudden spike in local pH and alkalinity when the caustic sodium hydroxide (Part 1) hits the tank water. This can cause a slow drop in alkalinity even though you keep increasing the dosage, because the alkalinity precipitates out of the water.

Why does it form? In low flow, the pH spike around the dosing point is much larger, which makes precipitation much easier. Dose Part 1 into a high-flow area of the sump, or use a small powerhead to help the solution disperse into the water quickly.