Coral Bleaching is Not Only Caused by Heat Stress

[jamesw]

Hi gang,

I learned the hard way that coral bleaching is not only caused by heat stress.

I had a slow but almost total bleaching event in my tank over the last 6 months that I couldn't explain. I finally realized what the problem was, and I corrected it an now my corals are darkened up and healthy again!

I believe that a number of factors were responsible for my coral bleaching:

• 1) Bad topoff water. My RO/DI membrane was 'toast' and I didn't know it. I replaced the membrane with a new unit.
  
  2) Low alkalinity. I was adding Kalkwasser to my makeup reservoir, but the reservoir was not sealed. The pH/alk of the Kalkwasser was dropping well before being added to the aquarium - thus it was pretty much doing nothing.

I knew there was a problem when the corals bleached, but it happened in the middle of winter, and my tank was a very stable 80degrees f. So I knew there had to be some other type of problem.

I decided that the thing to do was a massive water change with synthetic seawater made from my new RO/DI. I changed 70 gallons of water from a total system volume of about 120 gallons. The other step that I took was to hook up a Nilsen reactor (made by Nicolas Will) filled with lots of fresh CaOH powder. I regularly add more powder as needed.

Result: my corals are colored back and looking healthy. I had a white M. digitata, now it is brown and green. I had a clear and green frogspawn, now it is brown and green, etc.

And of course, my frags are growing like gangbusters again which is always nice.

Moral of this story:

• Good topoff water IS really important.
  Keep that alkalinity up for healthy corals.

Anyone have similar experiences?

Cheers
James Wiseman

 

[Anonymous]

Definately,


I was not paying much attention to my DI units water quality and I did notice my softies start getting very slack and they would close more often. After testing the DI water I noticed that it was not removing all of the phos and silicates any more. The water was very close to tap water. After replacing the resin,the softies responded immediately.

I also had another experience when I knocked the remainder of my Kalk powder into the sink ruining all of it. For a few days I used Baking soda and liquid Ca additions for makeup water. The PH was very unstable for a few days and even the fish looked bothered by it. After going back to Kalk the tank was normal again.

 

[jamesw]

Hi Buff,

I'm talking specifically about Coral Bleaching. See Eric Borneman's article in Advanced Aquarist entitled "White Corals" for a fuller explanation of the phenomenon.

Cheers
James Wiseman

 

[Minh Nguyen]

James,
IMO, coral bleaching can occured from any stress. Temperature, chemical or other causes. If the problem is not corrected than the coral will die.
BTW, I recently got a TDS meter. It is a really nice cheap piece of equibment to have to check and make sure the RO membrane is in good condition (often got ruin because we are to lazy to replace the carbon prefilter and let Clorine or Chloramine get to the membrane)

 

[Anonymous]

Possibily this is a common factor. Possibly more attention needs to be paid to alk/PH. But I will pay attention to my LPS if my alk/PH is out of wack.

 

[Cakepro]

Minh,
I hear ya about the TDS meter...I just bought one for $22 from www.h20instruments and it saved me from trashing all of my filters prematurely. I figured it was "about time" for another filter change...the meter keeps me from guessing now.

I keep a thick sheet of plastic on the surface of my kalk water to keep the C02 from making my makeup water impotent, since I make 7 gallons at a time and drip that in over 4 to 5 days' time. I too wasted some kalk water before keeping it covered. :roll:

I believe I'm losing some of my sps to bleaching because my CSL bulbs aren't living up to their 12 month lifespan (which I know isn't absolute).

I've got new ones on the way and am replacing them at 9 months from now on.

~ Sherri

 

[mwm6]

I have experienced some bleaching with a couple of my original species. I ran 400w Iwasaki's for the first 18 months, with great growth and acceptable coloration based on the 6500's. I decided about 3-4 months ago that I wanted to aesthetically improve my tank so I replaced the 6.5KK's with 10KK. My blue tip stag, along with two other acro colonies, have slowly bleached out on the top portions of all arms (areas receiving direct light). I have fragged the colony and located frags high and low with no success in bringing coloration to the arms (still gets blue tips - but previous growth goes mainly white). A once rose colored acro (under 6.5KK's, which went almost tan under 10KK, is now turning green in some locations as I've also scattered frags in the tank)

I have added a fair amount of frags since I changed lights and none of the new frag species are showing signs of bleaching. So, in my case, a drastic change in UV, or perhaps just spectral variation, may have contributed to the event, as no other tank parameters were outside the norm, and my lamps are at a fixed elevation in hood, although photoperiod was initially reduced.........................

 

[MFisher]

I've had a number of bleaching events of one or more corals. The common denominator in all of these was heat. This is not to say that they don't bleach for other reasons. Heat is likely one of the biggest reasons aquarists will encounter bleaching.

I don't think that the heat is the problem, persay. My tank used to get into the low 90's without any problems. As my tank maintainance got a little sloppier (old lights, old RO, less Ca supplements, less feeding, high salinity etc., etc.,) then I began to see bleaching coincide with periods of high temp.

The bottom line, by my estimation, is that heat is a tolerable stress as long as it is not coupled with other, chronic, tolerable stresses.

BTW I have a leather that has bleached portions of its capitulum on a fairly regular (circa 3 month) period for several years???

Matt

 

[MiNdErAsR]

Good topoff water IS really important.

Tell that to all the people running straight tap water in their successful systems.

Keep that alkalinity up for healthy corals.

Couldn't agree more.

 

[Minh Nguyen]

Good topoff water IS really important.

Tell that to all the people running straight tap water in their successful systems.

They will have sucess for short term only. No more than 2 years unless they continue to do massive water changes very often. There is too much impurities in most tap water including copper. The build up of this will kill everything. I have never heard of anyone who have sucessful reeftank for more than 3 years, that top off with just tap water and not changing, large amount of water (30%) or more monthly.
If there are, let them speakup.

 

[Bill2]

I think many things can lead to a bleaching type situation and catastrophic bleeching events are due to a lot of factors coming into effect at one unfortunate manner.

 

[Anonymous]

They will have sucess for short term only. No more than 2 years unless they continue to do massive water changes very often. There is too much impurities in most tap water including copper. The build up of this will kill everything. I have never heard of anyone who have sucessful reeftank for more than 3 years, that top off with just tap water and not changing, large amount of water (30%) or more monthly.
If there are, let them speakup.

I wish I didn't know of one exception! There was a woman some years ago in Atlanta who would show up to the meetings and she was always like "Duh, I don't know what I have in my tank".... and she only used tap water. She had the most beautiful tank ever. It was well established and had huge corals that had grown up in her tank. Others at the meetings were spending $10K on their setups and RO's and had no success. Infuriating.

And rare. I for one started a tank on tap and know it is a huge mistake. I will only ever use RO.

 

[Anonymous]

Just some quick info from a labnut who studies coral bleaching:


True coral bleaching is a term used to describe the loss of the symbiont dinoflagellate algae Symbiodinium (=zooxanthellae) from the coral host.

This only occurs to our knowledge when one of the organisms is being harmed, usually the host. Because the zoox have such a passive role, we currently think that the host is more instrumental in the actual act of expelling the symbiont partners (zoox). Why would a host do this? If the host is not receiving adequate nutrition from its endosymbionts, then they may end up competing for nutrients, and even oxygen during dark respiration phases. Or the host could be making way for a different strain of zooxanthellae that may be better adapted to the current environment (light, temp, nutrient levels, etc). These strains are known as Clades and their is a genetic basis to suggest their are 5 different clades (A-E) right now with numerous "species" of zoox in each clade. Some are more suited to low light, some high light, temp, etc. The details are still to be determined.

Classic bleaching occurs when corals are subjected to elevated temps. This causes a breakdown in the Photosystem II process within the zoox. The result is roving free radicals (superoxides usually) that wreak havoc on the host tissue. This oxidative stress causes a response whereby the corals expel or lose the algae.

Bleaching can occur for many more reasons, whether because the host is stressed from the environment or recent changes, or because the symbiotic algae are stressed or affected and thus, vicariously, so are the hosts.

Within the realm of aquaria, I think the most common causes of bleaching are:

1) heat (check and replace your heaters/chillers/fans frequently)
2) not replacing a burned out light quick enough (host and symbionts must both respire and are competing for O2 within the tissue of the coral)
3) slow degradation of lights (keep them fresh every 6-12 months)
4) increasing nutrient levels (do water changes with good quality water)
5) stray voltage in the tank (effects many chemical levels and ionic exchange balances in the animals and algae)
6) introduction of a toxin (wash hands, no chlorine, etc)

I think that's about all I can come up with right now.

 

[MiNdErAsR]

They will have sucess for short term only. No more than 2 years unless they continue to do massive water changes very often. There is too much impurities in most tap water including copper. The build up of this will kill everything. I have never heard of anyone who have sucessful reeftank for more than 3 years, that top off with just tap water and not changing, large amount of water (30%) or more monthly.
If there are, let them speakup.

Hi Minh,
Ask Dr Ron Shimek about the water he uses. AFAIK...tap.

 

[Minh Nguyen]

Hi Minh,
Ask Dr Ron Shimek about the water he uses. AFAIK...tap.

He also change water alot I believe. I can be done if one change water alot and/or do 100% water change once in a while. I never said that it cannot be done, just that the water change have to be enough to prevent build up of these impurities in the water.

 

[MiNdErAsR]

Minh,
In your original post you wrote...

They will have sucess for short term only. No more than 2 years unless they continue to do massive water changes very often. There is too much impurities in most tap water including copper. The build up of this will kill everything. I have never heard of anyone who have sucessful reeftank for more than 3 years, that top off with just tap water and not changing, large amount of water (30%) or more monthly.
If there are, let them speakup.

I mentioned Ron Shimek's tank as one such exception to your "short term" statement. Then your response to me was...

He also change water alot I believe. I can be done if one change water alot and/or do 100% water change once in a while. I never said that it cannot be done, just that the water change have to be enough to prevent build up of these impurities in the water.

If tap water contains "too much impurities", how would massive water changes alleviate the problem? I would think this would tend to maintain elevated levels of impurities. How would there be a "build up of impurities" if one chose not to do water changes? Wouldn't skimming and natural biological processes eventually reduce said impurities?

You may not have said it cannot be done, but your original statement certainly implys it! I was merely trying to point out that it can be done. However, I wouldn't recommend someone without a reasonable level of reef keeping experience try this.

 

[jamesw]

Adding tapwater to your tank that has .01% of something bad (i.e. copper) will slowly INCREASE the concentration over N days. Your concentration of the nasty goes up at N^1+.0001 Try putting in various N's and see what you get.

Doing a massive waterchange will bring the concentration down, but only to .01%

Hope that makes sense. It does to me, but I have done these types of calculations before in my line of work.

Jim: have you ever seen Ron Shimek's tank(s)? Have you ever seen a picture of one of them? If not, then I don't think it's a good example. If you want, I can show you some pictures of my tank when I was using tapwater for topoff...it looked like crap.

Cheers
James

 

[Minh Nguyen]

Jim,
I think you should read my first post carefully.
Regarding the build up of impurities, I am mainly worry about heavy metals, let us consider this example. Suppose I keep a 100-g reef tank that evaporates 2 gallons per day. I use 2 gallons per day because this is how much my 100 g tank evaporated. This number is critical in my calculation below.
When I first mixed the water with the very best salt mix, I use pure water with 0 amount of this metal X. Metal X is deadly to coral and many marine lives at some low concentration. However, it is not toxic to human, so the water commission does not care about the amount of this metal in the water. Because of this, there is a small concentration of this metal in the tap water. As I add tap water into the tank to replace the evaporated water, the concentration of this metal builds up.
Let say I change 10% water every month- 10-gallon. I use tap water and the same salt to mix these 10 gallons.
In an average month of 30 days, I added a total of 70 gallons of tap water into my tank (2 gallons each day and 10 g for water change) while removes 10 gallons. When the tank at steady state with regarding to this metal, the total metal X removed have to equal to the total amount put in. If the concentration of the metal X is 1 unit per gallon in tap water, I put in 70 units each month. This means that in order to removes 70 units; the concentration of the metal X in the tank is 7 units/gallon (10gX7units/g=70 units). The steady state concentration of certain impurities in a tank that have water change of 10% per month is 7 times that of the top-off water.
For a tank with 10% water change every 3 months, the concentration at steady state of this metal is 19 times the concentration of top-off water. If we don’t change any water, then the sky is the limit. On the other hand, if we do a 100% water change every year, then the concentration of the chemical will be back down to 1 unit when we finish (if we use tap water)
It really does not tank long for these chemical to get to the steady state lever. If we don’t change any water, it only tank 350 days for the chemical to go from 0 to 7 units of concentration in the tank water. Assuming that a tank evaporates the same amount as my tank, I guess if one can set up a tank and do no water change, and using tap water as top-off water for 1 years, and the tank do well, than that person can use tap water to keep his tank, provide that he does 10% water change per month.
This does not tank in other factors such as sequestration of these chemical by substance in the tank which make changing water an in effective way of removing these chemical. For example, for copper, we know that the substrate bind to the copper and remove lot of it from solution, only to be release when the pH drop. This means, that when copper enter the tank, it is there to stay to be release in the middle of the night when the tank pH is lowest.
There are many substances that would meet the criteria of chemical X, copper being one of them. For that reason, I believe that with out regular large water change, a reef tank cannot be keep with tap water as top-off water unless one do large water changes often. I STATED EXACTLY THIS IN MY FIRST POST. Keep in mind that some of these metals are toxic at very, very low level. Please don’t ask which metal or ions, because we have no idea. Anyway, the RO membrane is very effective in removing these heavy metals from the water.
Skimming only removes organic and larger compounds. It does not remove toxic metal ions and trace elements. Trace elements and these ions may be the same.
Anyway, it is late and I am sleepy. I am going to bed.

 

[MiNdErAsR]

Jim: have you ever seen Ron Shimek's tank(s)? Have you ever seen a picture of one of them? If not, then I don't think it's a good example. If you want, I can show you some pictures of my tank when I was using tapwater for topoff...it looked like crap.

Actually no I haven't. I can only go by what he states and I have no reason to doubt him. My very first reef tank was done with pure tap water (albeit from a private well), but it turned out ok.

Regarding the build up of impurities, I am mainly worry about heavy metals, let us consider this example....

This is exactly the response I was trying to elicit. Excellent post!