Interesting HLLE observation!

Beefyreefy · Feb 27, 2025

I will preface this with the fact that I know correlation does not equate to causation…. However, I really think I observed charcoal/carbon use directly causing HLLE rapidly developing on my hippo tang. I have never had an issue with HLLE before and I have kept many species of Tangs over the last decade in the hobby. I feed a mix of high quality frozen, high quality pellet, lots of seaweed and live black worms when I can get them. I don’t run a ton of additives or mechanical filtration, and have a fairly simple reefing method (lights, rock, skimmer, flow, and calcium/alk supplementation). I had a bad outbreak of red planaria worms that I finally decided to treat with Flatworm Exit. I was overly concerned about toxicity from dead flatworms so I did a large water change and placed sever large bags of carbon into the display and sump. Everything seemed fine so I went to bed. Unbeknownst to me one of the bags some how broke off from where I tied it and opened into the display over night. Woke up to charcoal all over the tank and the water had the distinct grey color that charcoal dust/particulate will impart on it. I believe it probably wasn’t rinsed quite enough and it didn’t help that it was sucked through the wave makers and spread everywhere. Despite being a huge mess to clean, I didnt think it was a problem. I sucked out what I could and filter flossed the water draining to the sump. Within a day water was crystal clear. Here is the issue though, my hippo tang I’ve owned for five years, almost instantly develops signs of HLLE! Over the course of 2 weeks, he developed patches under his eyes and black marks and pitting all over. Fortunately it seems to have stopped and is stable at this point (it’s been a couple months). I know there is a debate that charcoal can cause this but in my case I’m pretty certain it was a direct factor. None of my other tangs or fish had any ill effects though, just the hippo, I do know they are quite susceptible. I realize there is other variables like FWE and dead planaria or whatever but it definitely seems like it was my charcoal mistake? Regardless, I feel like my story could be of use to others… be extra careful with bags of charcoal! I’ll take any tips as well to help me reverse it!

vetteguy53081 · Feb 27, 2025

Beefyreefy said:
I will preface this with the fact that I know correlation does not equate to causation…. However, I really think I observed charcoal/carbon use directly causing HLLE rapidly developing on my hippo tang. I have never had an issue with HLLE before and I have kept many species of Tangs over the last decade in the hobby. I feed a mix of high quality frozen, high quality pellet, lots of seaweed and live black worms when I can get them. I don’t run a ton of additives or mechanical filtration, and have a fairly simple reefing method (lights, rock, skimmer, flow, and calcium/alk supplementation). I had a bad outbreak of red planaria worms that I finally decided to treat with Flatworm Exit. I was overly concerned about toxicity from dead flatworms so I did a large water change and placed sever large bags of carbon into the display and sump. Everything seemed fine so I went to bed. Unbeknownst to me one of the bags some how broke off from where I tied it and opened into the display over night. Woke up to charcoal all over the tank and the water had the distinct grey color that charcoal dust/particulate will impart on it. I believe it probably wasn’t rinsed quite enough and it didn’t help that it was sucked through the wave makers and spread everywhere. Despite being a huge mess to clean, I didnt think it was a problem. I sucked out what I could and filter flossed the water draining to the sump. Within a day water was crystal clear. Here is the issue though, my hippo tang I’ve owned for five years, almost instantly develops signs of HLLE! Over the course of 2 weeks, he developed patches under his eyes and black marks and pitting all over. Fortunately it seems to have stopped and is stable at this point (it’s been a couple months). I know there is a debate that charcoal can cause this but in my case I’m pretty certain it was a direct factor. None of my other tangs or fish had any ill effects though, just the hippo, I do know they are quite susceptible. I realize there is other variables like FWE and dead planaria or whatever but it definitely seems like it was my charcoal mistake? Regardless, I feel like my story could be of use to others… be extra careful with bags of charcoal! I’ll take any tips as well to help me reverse it!

This is an absolute and seen many times especially when there is carbon dust and particles why I run any in my sump furthest from the return pump. Deal with the flatworms first and do a series of water changes which I recommend 5 gallons a day for 10-14 days.

Jay Hemdal · Feb 27, 2025

Beefyreefy said:
I will preface this with the fact that I know correlation does not equate to causation…. However, I really think I observed charcoal/carbon use directly causing HLLE rapidly developing on my hippo tang. I have never had an issue with HLLE before and I have kept many species of Tangs over the last decade in the hobby. I feed a mix of high quality frozen, high quality pellet, lots of seaweed and live black worms when I can get them. I don’t run a ton of additives or mechanical filtration, and have a fairly simple reefing method (lights, rock, skimmer, flow, and calcium/alk supplementation). I had a bad outbreak of red planaria worms that I finally decided to treat with Flatworm Exit. I was overly concerned about toxicity from dead flatworms so I did a large water change and placed sever large bags of carbon into the display and sump. Everything seemed fine so I went to bed. Unbeknownst to me one of the bags some how broke off from where I tied it and opened into the display over night. Woke up to charcoal all over the tank and the water had the distinct grey color that charcoal dust/particulate will impart on it. I believe it probably wasn’t rinsed quite enough and it didn’t help that it was sucked through the wave makers and spread everywhere. Despite being a huge mess to clean, I didnt think it was a problem. I sucked out what I could and filter flossed the water draining to the sump. Within a day water was crystal clear. Here is the issue though, my hippo tang I’ve owned for five years, almost instantly develops signs of HLLE! Over the course of 2 weeks, he developed patches under his eyes and black marks and pitting all over. Fortunately it seems to have stopped and is stable at this point (it’s been a couple months). I know there is a debate that charcoal can cause this but in my case I’m pretty certain it was a direct factor. None of my other tangs or fish had any ill effects though, just the hippo, I do know they are quite susceptible. I realize there is other variables like FWE and dead planaria or whatever but it definitely seems like it was my charcoal mistake? Regardless, I feel like my story could be of use to others… be extra careful with bags of charcoal! I’ll take any tips as well to help me reverse it!

Sorry to hear.

I’ve run into a few cases of acute HLLE caused by massive carbon spills. In one case, a public aquarium decided to fill their sand filters with carbon, each backwash ground up the carbon and jetted it out into the tanks. Fish were actually dying from secondary bacterial infection of the lesions.

It is REALLY tough to get all the carbon dust out of a tank without stripping it completely down, throwing out all substrate and rinsing all the corals and rocks in clean seawater.

One option might be to just avoid HLLE prone fish for that tank.