A picture of a reef by user Thijsvb that would be a total shame if an aquarist had lost it due to an uknown problem.
In writing this first article of mine, id like to help people to investigate unknown reef conditions to find the cause and hopefully the solution.
How often do I hear, "im at wits end", or "im not sure whats going on", is all too often. The fact is this hobby is full of pleasure and pain. Losing an entire tank full of coral or fish in a short time thats been growing for years, is very heartbreaking and to be honest completely unnecessary.
Rtn/stn of corals:
The first thing to do here is to check all your water parameters. Do it newly and do not rely on a previous result. That should be the golden rule of reefkeeping, "never assume." So go and test everything we can possibly test for with hobby tests again. Alkalinity, calcium, magnesium, potassium, salinity, ph, temperature, etcetera.
As you get them all freshly tested, write them down so you don't forget. Now if everything tests out in the normal range then proceed to step two.
Step two: verify your tests accuracy. Sometimes by user fault or by the manufacturers fault, test kits or testing equipment can give inaccurate results. For example if you leave the acid cap off it will evaporate leaving a stronger solution and provide a false reading. Also be sure the test kit isn't expired.
For a refractometer calibrate it with 0 tds ro/di water. Be sure this is the recommended manufacturer's way. Make sure to let the sample sit for 5 minutes to automatically temperature compensate. Adjust the calibration screw if necessary. An even better option is to use a salinity standard which you calibrate your refractometer with and is closer to the point which we are reading (35 ppt or 1.026 Sg) which can be made yourself and is detailed in articles by Randy Holmes-Farley. If you're not interested in diy, you can buy one. Test the salinity again and adjust if necessary.
Now if salinity is good, test your alkalinity test kit. This is easy to do. Go to the grocery store and buy a box of baking soda, the only ingredient it should say is sodium bicarbonate. Now get a 1 gallon jug of distilled water. Put in 1.035 grams of baking soda into the distilled water jug. Shake it up. Write on it 10dkh. This will be your diy alkalinity standard and when you test your kit with it, the kit should read close to 10dkh. Make sure you use a scale with a reading of .001. If you don't have a scale like this, just ask a pharmacist to do it at the store you bought the baking soda at. They have very good scales and will do it free. Test your alkalinity kit with this baking soda water. This may not or may work for the Hanna alkalinity Checker, but will work with standard acid based titrations like Salifert, API, or Seachem. You will then know if your alkalinity test kit is accurate or not after you titrate it with your new "baking soda" standard. Imo the kit is good if it falls within 1dkh. If its more than that id suspect a bad kit. IIRC Randy Holmes Farley also has a diy alkalinity standard recipe in much greater detail than here, so you might want to read that. This recipe is just a "emergency recipe", and the actual recipe requires you to be much more accurate, but imo serves fine for this purpose.
Now if alkalinity and salinity are good, you need to find another source of the problem. Imo salinity and alkalinity are the two most stressful factors, the next you should test is potassium. Algae, bacteria and coral will consume potassium and if you're not doing water changes, potassium will get depleted. I don't have a diy standard for this but you could ask Randy in the chemistry forum if you want to double check it. Be sure it is between 380-420 ppm.
Now test your magnesium, what's it read? Be sure its between 1200-1300 ppm. As much as 1400 ppm is fine but imo anything more and you're asking for trouble.
If calcium, alkalinity, potassium, magnesium, and salinity test good, then check out your phosphates and nitrates and ph.
Also be sure to calibrate anything like a ph meter newly. If using Hanna checkers be sure you're not re-using old tank water you left in the vial to "zero" it.
Next you'll do a run down of your equipment. Check that nothing is rusting. Take out all your pumps, and do a dunk test in a bucket of water see if any rusty silt comes out from the pump "cap". This is where the electric cable goes into the pump. Then open the pump and check the impeller isn't badly rusting. Do this for all pumps, powerheads and other electronic motor like equipment.
A picture of a Maxspect Gyres electric cable exposed to water.
Now also check the electric cables of the pumps, make sure there is nothing wrong with them, bend the cable to find any cuts or splits in the plastic sheathing. A sea urchin can chew threw an electric cable. And the plastic can deteriorate too. Check near where the cable enters the pump too because the cable can get pulled out. Don't forget to check any pumps that run on calcium reactors. Most pumps use copper wire and copper equals death in a tank.
Next do a stray voltage test. You'll need a multimeter to do this. Ask on Reef2Reef how to do it.
If all is good with pumps, now check your lights for salt crust that may be coated in metals from the light and possibly fall into the water with the accompanying metal. All good?
Check your magnetic algae glass cleaners for swelling as they can also have metal that can enter the tank from the magnet.
Now that you've done that get your hands on a powerful magnet if you can. The bigger the magnet the better. Try to use a plastic coated one to avoid exposing metal to the water. Run it over your sandbed. See if it picks up any screws or metal bits. Take them out if you find any. Now if its aluminum or copper the magnet wont find it as its not magnetic. So you can use a sort of rake and rake through the sand bed, but it's not good to disturb the sand bed for a lot of reasons. So skip this step if wanted. But if you have a thin sand bed it shouldn't be a problem imo. A fine tooth comb sounds good to me.
Check your heaters for any hairline cracks in the glass or damage.
Next thing is ask yourself "what have I recently added?" Have you added anything new? Phosphate remover or any chemicals? Sponge? Filter floss? Did you spray paint something? Add a new rock? Have you just started to dose an organic carbon like vodka or vinegar? Have you changed brands of buffer, or any other supplements? Added new pipe? If you've added anything different stop with that or take it out. If you've added a new supplement go back to the old one that worked, as the new may have an impurity causing problems. If you've added anything new in the last month id suspect that as a possible culprit.
If you are using any kind of dosing pump be sure to calibrate any necessary equipment related to dosing. For example a ghl profilux dosing pump can be calibrated. Over time tubing can become plugged too reducing its dosing.
By now I hope you have found something. Due to the limitations of hobby test kits, if you still haven't found anything id recommend sending a water sample off to an ICP company. This will give you a clear picture of anything that might be off. For example if your dosing magnesium sulphate (epsom salts) but not dosing magnesium chloride, sulphate will increase higher than it should be. An Icp test will tell you those things.
If you've recently added anything made of aluminum a lot of corals may not like it. Like Marinepure bricks or Seachem's phosphate remover, which is made of aluminum oxide.
In the event that you've found something bad a 60% or more water change isn't a bad thing imo when everything is going wrong. Putting a fire out slowly isn't going to effect the char made.
If you've detected heavy metals, a water change of 80% and a metal adsorbing media like Metasorb may work good. Also activated carbon is paramount in reducing coral toxins. So you might want to use that too. If in the event that you've detected a split electrical cable, copper may have entered the tank. Seachem Cuprisorb should help with that as well as a large water change.
Good luck and happy reefing!