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Tag: Ca

  • Why I Started Measuring Water Parameters with a Salifert Test Kit

    The water looks clear, but why are there days when corals stay a little less open than usual, or livestock behave differently?

    While keeping a 45-cube reef tank, the most frustrating moments were probably when I couldn't figure out the cause of what was happening in the tank.

    Dealing with hitchhikers, deciding on a water change schedule, and dealing with algae growth are all difficult, but for me, the hardest part was the time when I had to guess at the reason corals or other livestock were doing poorly.

    A reef tank with torch coral, bubble coral, globe polyps, Acan coral, and star polyps.
    The tank back when the globe polyps and bubble coral were growing healthily.

    For about a year after starting the 45-cube tank, I was watching the tank's condition with my eyes and my gut. Temperature and salinity are relatively simple. They're easy to measure, and you can immediately understand why they matter without anyone explaining it to you.

    But I kept wondering whether the values people commonly call water parameters really needed to be measured at all. Each one needed its own test kit, and the testing methods looked more difficult than temperature or salinity, so I kept putting it off.

    Then something happened. I did a water change at the same time and in the same way as usual, but after the water change, white spots started appearing on the fish, the tips of the globe polyps that used to open fully no longer opened, and brown algae gradually started covering the globe polyps.

    A photo of the globe polyps when they were very healthy and fully open.
    A photo of the globe polyps with the polyps folded in.

    I especially knew something was wrong when Nemo, who had been eating well and breathing normally, stopped eating and started breathing harder and harder.

    I searched online. Since I kept seeing people say to do a water change if something seemed wrong, I started doing a water change once a day, and thinking the corals might be lacking oxygen, I hurriedly bought an airstone and added bubbles too.

    A tank photo with the airstone running.

    With the airstone running and daily water changes, things seemed to improve a little. Then, when I looked at the tank after work with a nervous feeling, I saw a dead fish. Not long after that, the globe polyps died too.

    After that, the bubble coral, the yellow tang, and the coral I called the bouquet coral suddenly started doing poorly too, and then were gone.

    A clownfish that suddenly died.
    Bubble coral just before the skeleton and polyp tissue separated.

    It was really painful. And I kept wondering what on earth was wrong. I had done the water change the way I usually did, so was the problem with the water change? Or was it something else?

    I remembered water testing, which I had felt wasn't really necessary. If I had tested the water, would I have been able to figure out what the problem was?

    I decided to start measuring the water. I wanted to figure out what absolutely needed to be checked in a tank where I keep corals and fish together, so from that point I looked a little more into individual parameters and decided to measure four high-priority ones.

    The four I decided to measure

    KH/Alk and Ca are closer to the side that helps corals build skeletons and stay stable. NO3 and PO4 are closer to the nutrient side connected to food, waste, filtration, and algae.

    Simply put, one is the flow corals use, and the other is the flow that stays in the tank and builds up there.

    • KH/Alk: alkalinity connected to pH buffering and coral skeleton formation
    • Ca: calcium that LPS and stony corals use to build calcium carbonate skeletons
    • NO3: nitrate left behind after food, waste, and biological filtration
    • PO4: phosphate connected to food, organic matter, and even the storage capacity of rock and sand

    I wrote up separate notes about actually running each test.

    • Salifert KH/Alk test instructions
    • Salifert Ca calcium test instructions
    • Salifert NO3 nitrate test instructions
    • Salifert PO4 phosphate test instructions

    KH/Alk: the buffering strength corals rely on

    The reason I looked at KH/Alk first was that I felt it was directly tied to coral response. KH is not pH itself, but alkalinity, which shows how well the water can resist shifts toward the acidic side.

    LPS like torch coral and Acan coral show water changes very clearly. When the polyps open less or the tissue looks shrunken, I can't say for sure that there's only one cause, but it is worth checking whether KH is swinging.

    When I first measured it, the value came out around 12.8 to 13.1 dKH, which was clearly higher than the commonly known 8 to 12 dKH range.

    Based on that value, I formed a hypothesis that the KH of the new water made for a 25% water change once a week was staying higher than what the corals were consuming, and that this repeated pattern was pushing the value up.

    After reducing the water change amount and testing for a month, the KH value actually moved into the normal range.

    Ca: the material corals use to build skeletons

    Ca is the main material in a coral skeleton. Even though LPS look fleshy and full, they still have a hard skeleton inside, and when they form new heads or thicken their skeleton, they use Ca and KH together.

    The most disappointing one was the bubble coral. The once-full bubble coral slowly separated between the skeleton and the polyp tissue over a very long period of time, until it finally separated completely. I think I might have made a better judgment if I had tracked that value.

    NO3: the residue left after processing food

    NO3 is nitrate left after food, waste, and dead organic matter go through bacterial processes.

    High NO3 doesn't immediately mean disaster, but if it stays high for a long time, it can be linked to increased algae growth or changes in coral color. On the other hand, it doesn't have to be zero either. Corals, symbiotic algae, and bacterial ecosystems also need some nitrogen source.

    PO4: a value that can affect both algae and coral growth

    PO4 is phosphate. People often associate it with algae, but phosphorus is also a nutrient needed for life.

    The problem is that the tank can become unstable whether it is too low or too high. If it's too low, the balance between corals and microbes can be disrupted, and if it's too high, it can be linked to glass algae, rock algae, and cyanobacteria.

    Moving from gut feeling to records

    A 45-cube tank with torch coral, star polyps, Acan coral, leather coral, Nemo, and a blue tang.

    Of course, not all symptoms that appeared in the livestock could have been found or prevented through testing.

    Still, it felt too frustrating to keep relying on gut feeling alone, and once I started measuring, at least I no longer looked at everything purely by instinct like before.

    I now had a reference point for seeing how the measured values were moving behind the visible changes, like whether the water looked clear, whether the corals were open, or whether algae was increasing.

    I hope the precious livestock grows better.

  • How to Use the Salifert Ca Calcium Test Kit

    I pulled out the Salifert Ca test kit to check the calcium level in the tank.

    The kit comes with a test vial, a 2 ml syringe, a 1 ml syringe, a plastic tip, the Ca-1 powder reagent, the Ca-2 liquid reagent, a special spoon, a chart, and the instructions.

    Salifert Ca test kit contents, instructions, vial, spoon, test solution, test powder, and syringes.

    Here is a quick summary of the testing steps.

    1. Put 2 ml of tank water into the test vial.

    Draw up 2 ml of tank water with the syringe. Try to draw it up as cleanly as possible, without bubbles.
    When transferring the water into the vial, do it slowly so it does not splash against the sides.

    Draw 2 ml of water. Try to pull it up as cleanly as possible, with as little foam as possible.

    When dispensing the water from the syringe into the vial, do it gently and slowly so it does not splash against the vial walls.

    2. Add one spoonful of the Ca-1 powder reagent with the special spoon.

    A generous scoop of the Ca-1 test powder in the spoon.
    After scooping up a generous amount of Ca-1 test powder, tap it lightly with your finger so the spoon is filled just right.

    As with other test kits, fill the spoon generously first, then gently tap it with your finger so the spoon ends up full.

    3. Gently mix the vial for about 5 seconds.

    The color after adding and mixing the Ca-1 powder.

    The instructions do not specifically say to mix, but if you do not, the Ca-1 powder remains in the water, so I gave it a quick mix.

    4. Draw the Ca-2 solution into the syringe up to the black tip at 1 ml.

    Check that the pink plastic tip is seated firmly.
    Check that the pink plastic tip is seated firmly.
    Line up the black tip area to the 1 ml mark. The solution level itself does not need to be exactly 1 ml.
    Set it to 1 ml based on the black tip.
    The solution does not need to reach 1 ml exactly.

    After firmly attaching the plastic tip to the 1 ml syringe, draw the Ca-2 reagent up to the 1.00 ml mark. At this point, align the lower reference line of the black rubber piston with 1.00 ml.

    It was written in the instructions, but at first I was not sure whether the reference was the solution level or the tip, so I searched it and confirmed that, as shown in the photo, you line up the end of the black tip with 1.00 ml.

    5. Mix 0.6 ml of Ca-2 reagent into the water.

    Put 0.6 ml of Ca-2 solution directly into the vial. Set the scale so the black line reads 0.4 ml.
    The solution turned from blue to pink after adding 0.6 ml.

    With the syringe set to 1.00 ml, add 0.6 ml into the vial. The black tip of the syringe will then line up at 0.4 ml, and the liquid in the vial will turn pink.

    6. Add the Ca-2 reagent drop by drop, swirling for about 1 to 2 seconds each time.

    Adding the Ca-2 solution drop by drop.
    Adding the Ca-2 solution drop by drop and shaking it for 2 seconds each time.

    Keep going slowly until the color changes from pink to blue. When it starts looking purple in the middle, it feels like you are very close to the end, so from that point on I had to be more careful and watch it one drop at a time.

    How to Use the Salifert KH/Alk Test Kit

    Like with the KH/Alk test, you need to watch the point where the solution changes color, and this time too I needed to record the exact moment the color clearly changed.

    I thought video would make it clearer, so I recorded one. You can clearly see the color change.

    Reading the 1 ml syringe scale after the Salifert Ca test.
    Compare the value at the end of the syringe's black tip with the chart.

    Once the color turns blue, hold the syringe with the tip facing up and compare the position of the black rubber piston with the chart to read the tank's Ca level.

    Based on the photo above, the black mark looks to be around 0.19, which puts the result at about 405, between 0.18 and 0.20 on the chart.

    This reading

    This Ca reading looked to be around 405 ppm.

    As with other Salifert kits, this is not a digital measurement, so the result may be a little different from the actual value, but it still seems important to measure it the same way each time so you can keep track of the number.