Gigantea's and magnesium

[phender]

I am not posting this as scientific proof, it's just something that has happened twice.

I am not a very high tech reef keeper and I have too many tanks, too little time and too many hobbies. I don't test my water as often as I should, nor do I do water changes very often. I don't have calcium reactor, but instead rely on the addition of 2 part solutions to maintain calcium and hardness levels.

That said, several months ago my gigantea took a nose dive for no apparent reason. It wasn't opening up as much as normal, wasn't very sticky and stopped eating. Everything else in the tank; H. magnifica, H. crispa, leather corals, LPS, zoanthid, mushrooms, ricordia, all looked fine. I did all my tests and I noticed that the magnesium levels were down to around 900 ppm. (For those of you who don't know, they are supposed to be at least 1300) As soon as I started adding magnesium, the anemones started to perk up. After about a week and the Mg levels started to get closer to normal the carpet was back to normal.

Last weekend the gigantea started to look bad again. Guess what, the Mg levels were down around 1100 ppm. I have been adding Mg everyday this week and it is almost back to normal once again. In neither case did I panic and do a bunch of things like a water change or increase flow or light or force feed. All I did was bring up the Mg levels.

I know there are not a lot of gigantea keepers out there, but it is something to check if your carpet that you have had for a while starts to go bad on you.

 

[BonsaiNut]

Thanks for posting this Phil.

 

[a4twenty]

very interesting, in a recent test of the new salt i have been using ( ~4months ) i noticed it seriously lacked in Mg. i also have noticed my gigantea acting a little weird lately and have been scratching my head to figure out whats off.

my Mg in the tank is a bit low but i haven't increased the amount i dose yet because i haven't had the time to do it properly ( daily test etc.... ) but i am going to start today.

thanks for the tip, i will give it a try, scientific or not

 

[Flighty]

I let my Mg levels drift very far down once after adding a lot of dry rock and having a big growth of the amount of coralline algae. It got low enough to effect all of my SPS and LPS, but my magnificas and mushrooms and zoas were not visibly effected.

 

[isseym328]

Hey Phil,

I do not check my Mg levels at all. Is Mg something that can be replenished with normal weekly water changes?

 

[a4twenty]

not to speak for phil........


most salts have poor Mg numbers, some worse than others. weekly water changes will help to maintain the level ( usually to low ) but i have always had to dose to bring them up to NSW levels.

 

[wicked_NaCl_h2o]

I always had to dose Mg with coralife salt. That was with weekly water changes. After dosing the tank with Mg, all the anemones would get big and happy.

 

[isseym328]

I actually don't use salt mixes. I buy natural sea water. Would it be the same either way?

 

[Toddrtrex]

<a href=showthread.php?s=&postid=13667317#post13667317 target=_blank>Originally posted</a> by isseym328
I actually don't use salt mixes. I buy natural sea water. Would it be the same either way?

It really depends on the Mag levels of the NSW that you are using. Would have to test it and see what you get. I almost never have to add Mag (( even with lots of SPS in my tanks )), the salt I use (( TM Pro )) has good levels of Mag.

 

[phender]

When I used NSW it seem as though all my levels (Ca, Mg, Alk) were always low. I have no idea why.
Now I use OceanPure Pro which has high levels of Mg, but you actually have to do water changes before it helps. It doesn't really help when its just sitting there in the pretty bucket.

 

[garygb]

Phender, I'm curious about the OceanPure Pro salt. Do you buy it online or from a lfs? I use ReefCrystals and I like it, but I'd experiment with that brand assuming the cost isn't prohibitive and it's easy to get.

 

[phender]

I got the 200 gal bucket from a LFS that is no longer open. When I run out I will have to do a search myself. I think Amazing Aquariums and Reefs in my area carries it, but that doesn't help you that much unless you make road trips to Orange County.

I know that the D-D H2Ocean Pro w/ Magnesium is getting pretty popular. You can get that at Marine Depot.

 

[garygb]

Thank you Phender, I also did an online search and saw where you can order the 200 gallon from Custom Aquatic, for 24.99 (shipping is around 20 bucks for me in L.A.).

 

[Randy Holmes-Farley]

Very interesting. I did a quick literature search and found nothing searching onon "Stichodactyla and magnesium".

I did find some articles which suggest a connection between divalent cations and certain anemone processes:



Calcium antagonists inhibit the discharge of cnidae in response to electrical stimulation in the giant tropical sea anemone Heteractis crispa Ehrenberger (Anthozoa). Dahl Hermansen, Tyge; Arvedlund, Michael; Fiedler, G. Curt. The Quality of Life Research Center, Copenhagen, Den. Marine and Freshwater Behaviour and Physiology (2005), Volume Date 2006, 38(4), 269-274. Publisher: Taylor & Francis Ltd.

Abstract

The mechanisms involved in cnidocyst discharge among cnidarians are not well understood. In this study the authors examd. the discharge mechanism in an anthozoan. The authors examd. the effect of the Ca2+ antagonists (Mg2+, Co2+ and La3+), a Ca2+ agonist (Sr2+), and two cations (Ca2+ and K+) upon cnidocyst discharge, using elec. stimulation applied directly to sea anemone tentacles. In this expt. the authors used the sea anemone Heteractis crispa, a known host for anemonefishes, as a model organism. The authors' results show that the Ca2+ antagonists effectively inhibit, while all the other cations enhance the cnidocyst discharge of H. crispa. These results are comparable to those from a similar study on the hydrozoan, Hydra vulgaris, which also used the electrostimulation method. The authors' results demonstrate for the first time that the discharge mechanisms in Anthozoa and Hydrozoa are comparable, and support existing hypotheses concerning the importance of Ca2+ in cnidocyst discharge.


Ionic effects on discharge of the isolated and in situ nematocysts of the sea anemone, Aiptasia pallida: a possible role of calcium. Blanquet, Richard. Dep. of Zool., Duke Univ., Durham, NC, USA. Comparative Biochemistry and Physiology (1970), 35(2), 451-61.

Abstract

Nematocysts were isolated from acontia by extrusion in 1.0M Na citrate. The high concn. was necessary to maintain the liberated nematocysts in an undischarged state. Isolated nematocysts were comparatively insensitive to stimuli which normally evoked their discharge in situ. This was true for solns. of low pH and high K ion concn. Both discharge and extrusion of in situ nematocysts could be reversibly abolished by pretreatment of the acontia with MgCl2. None of the salt solns. tested caused appreciable discharge of isolated nematocysts at an osmotic strength equal to that of seawater. Increasing dilns. of these solns., however, caused a progressive increase in discharge. Divalent cations, such as Ca and Mg caused a marked inhibition of this effect, and may play a role in a nematocyst stabilization.



Physiological mechanism of nematocyst responses in sea anemone. III. Excitation and anesthetization of the nettling response system. Yanagita, T. Ochanomizu Univ., Tokyo, Comparative Biochemistry and Physiology (1960), 1 123-39.

Abstract

The cnidae situated in the acontial filaments of the sea anemone, Diadumene luciae, respond by eversion of the stinging threads to K+ or NH4+ in the external medium, to elec. current and to mech. contact of such solid matter as food objects, human hair or skin, and cholesterol. These agents were without effect on the cnidae which had been isolated from the acontium. The responses of the cnidae in situ were prevented reversibly by Mg and org. anesthetics. The presence of Cl- in the external medium was a necessary factor for establishing the explosion responses of cnidae in situ, and that the stimulating agents could produce only "misfiring" extrusion of cnida bodies, when they were made to act in a medium which was poor in Cl content.


The method of narcotization for the sea anemone, Anthopleura xanthogammica, and the echiuroid, Urechis unicinctus. Fujii, Sakiko; Isaka, Saburo. Univ. Chiba, Chiba Daigaku Bunrigakubu Kiyo Shizen Kagaku (1957), 2 235-8. From: Biol. Abstr. 35, Abstr. No. 38376(1960).

Abstract

The sea anemone was narcotized when 20 ml. of 0.81M MgSO4.7H2O were added drop by drop in 20 hrs. to 200 ml. of the medium sea water. A similar but a little inferior effect was obtained with 0.81M MgCl2.6H2O. Lack of Ca and K ions caused narcosis in 20 hrs. A prolonged addn. of KCl, to the final concn. of 0.215%, narcotized the coelenterate. The echiuroid was narcotized after 24 hrs. in 0.17M MgSO4 or MgCl2. Ca ions had the denarcotizing effect.



Physiological mechanism of nematocyst responses in sea anemone. VII. Extrusion of resting cnidae-its nature and its possible bearing on the normal nettling response. Yanagita, T. Ochanomizu Univ., Tokyo, Journal of Experimental Biology (1959), 36 478-94.

Abstract

The acontium of Diadumene lucia extruded its nematocysts (microbasic p-mastigophores) when placed in sea water dild. 20 times or more with distd. H2O or with some nonelectrolyte soln. The effect of diln. of sea water was caused by the decrease in concns. of Cl and Br ions which act on the surface of acontium to suppress the extrusion. A similar effect of suppressing the extrusion was also found with many other univalent ions; most of the multivalent ions lacked such effect. The cnida extrusion could be anesthetized with Mg++ ions or with many org. anesthetics. This anesthesia was reversible.

 

[Randy Holmes-Farley]

For folks who want to make a big boost to magnesium, it can be incredibly expensive and takes a very large amount of additive (enough that many folks are reluctant to actually add that much).

For that reason, there is a DIY recipe here, and the calculator below tells you how much you'd need to add of many DIY and commercial supplements:

Reef chemicals calculator
http://home.comcast.net/~jdieck1/chem_calc3.html

Do-It-Yourself Magnesium Supplements for the Reef Aquarium
http://reefkeeping.com/issues/2006-07/rhf/index.php

 

[isseym328]

Great info Randy. Thanks!

 

[Randy Holmes-Farley]

:thumbsup:

Happy Reefing.

 

[schprock]

If you are running a calcium reactor, adding dolomite in your reactor will work also.

I use instant ocean which is notorious for low Mg++ but am able to keep Mg++ above 1300 with dolomite.

Dolomite used to be found in all stores but is no longer in fashion today. Some store owners have never even heard of dolomite. But, premium aquatics carry them, and a 20 lb bag from them will last a long time.

IME, sps growth rate is a function of Mg++ as well.