Cant fight algae in dt

[kotlec]

Blue with white spots



Green acro single spot in the middle. As you can see birdsnest also has bad PE



Spoted , but dont know if its dead spots or just polyps retracted. Not so obvious



Green still has small PE at the top :



Semi retracted :



This look good, just pale as usual :

[Floyd R Turbo]

Other elemental deficiencies - When discussing elemental deficiencies, potassium comes to mind. Because I am a "color hunter", I test for potassium weekly and dose it on a dosing pump. Potassium plays a role in tissue building rather than skeleton formation. A potassium deficiency will first show its face in the loss of pocillopra and stylophora corals. Montipora corals will grow very slowly and may lose their once vibrant colors. Acropora corals of blue and purple varieties will seam pale in appearance. Red corals will being to pick up a grey appearance to them. Advanced potassium deficiency will lead to dry appearing flesh and loss of tissue from the tips-down.

This one I find particularly informative. I also feel that this is a key element that needs to be dosed in tanks that run algae scrubbers long term. N-P-K = plant growth.

[kotlec]

Found mine at 360, when I tested for first time. Now have it at 390.

[M I N I O N]

This one I find particularly informative. I also feel that this is a key element that needs to be dosed in tanks that run algae scrubbers long term. N-P-K = plant growth.

This is very true. Anybody who is dosing a carbon source or harvesting macro algae as a replacement to water changes needs to be dosing potassium. I would even recommend running higher than natural sea water levels of potassium in these situations. This is one of those elements which in normal conditions, does not get depleted but rather "passed around" in a sense. It is used in the formation of coral tissue but but not at an appreciable rate where you may find depletion. In the case of harvesting bacteria or algae to reduce nutrients, you are directly pulling potassium out of the system with the algae or bacteria.

[M I N I O N]

Kotlec, looking at your pictures, I would be testing for stray voltage.

[kotlec]

How to test it ?

[M I N I O N]

If you have a grounding probe, take it out. Stick the ground probe of a multimeter in the ground pin (the bottom on) of a surge protector strip plugged into the wall. Stick the positive into the display tank. You'll want to test it on both AC and DC voltage settings. If you register voltage, unplug the components of your tank one at a time until you see it drop.

I don't recommend doing the "wet feet and a hand in the tank" method because a bad voltage leak can kill you.

[greenmachine]

If you have your system running on a GFCI there is no stray voltage. You can not just test the water for voltage ,there will always be something there due to the ions in the water. Don't believe me? Try testing a bucket of mixed salt water with no power in it...

[kotlec]

Measured water to ground.

DC =0
AC = 0.1-0.2 V. If I touch tank glass with a finger voltage jumps to 0.7V

Does it means something ?

Edit: After some more reading , I thing what I am measuring is induced voltage and not stray .

[M I N I O N]

I don't think you have enough induced voltage to cause problems, though it could be introduced at random and wasn't present at the time. It would still be a good idea to put a ground probe on the tank. The next thing I would do in your shoes would be to perform a few large water changes with a high quality salt mix. I prefer Kent because it has elevated levels of minor ions such as potassium which will regularly get pulled out. After doing this, inspect your corals very well for pests.