View Full Version : Source of Metals (believed unknown)-Long Story

03/13/2013, 09:28 PM

Due to my interest in clownfish/anemone hosting, symbiosis and anemone survival I have began testing additional parameters. I was mainly worried that my pH was too low as it hits about 8.0 and that's as high as it goes. I got some Tetra test strips which measures Alkalinity as well. In my 90 gallon tank that has been up for 1.5 years (Current USA light, 4X 65W bulbs, two 10K, two actinic, aragonite sand, lots of live rock, etc.) all the levels were good.

In a newer (ca. 3 months) 29 gallon where I keep one anemone and two clowns the Alkalinity was off the charts above the 300ppm as shown on the test strips. Since I just put a new GBTA in, I started to do a water change. After getting the salt in I checked the alkalinity and it too was off the charts so I didn't do a water change.

I tested the tap water and it too showed >300ppm alk. I called the water department to see if anything was going on there. He said their alkalinity is supposed to be delivered at 50 ppm. It turned out he had 15 tanks at one time so he knew saltwater and fresh. We talked a long time and couldn't figure it out.

At the end of the conversation he asked if I used the HOT water when doing water changes and I said YES because I tried to match the tank water temperature. He said, the sacrificial electrode (galvanic electrode) in the hot water tank may very well contribute to the alkalinity. It turns out that sacrificial electrodes are either Magnesium or Zinc-Aluminum. Upon oxidation these produce their respective hydroxides which would be rather basic and thus contribute to the alkalinity.

I went to the faucet and ran the cold water for awhile, collected some and it tested NORMAL for alkalinity.

Thus, its obvious that alkalinity and/or toxic metals can come from your HOT water heater. Clearly, the lesson is to never use hot water!

The secondary lessons would be to get an RO/DI unit and/or pre-prepare the WC water the night before (as has often been recommended).

Now I have the 29 and two brand new 55's with this water in them. Looks like I'll be draining them all or attempting chelation (I do have some citric acid and since it chelates copper it should chelate magnesium, zinc and aluminum; all soft metals). I will be trying this on a sample of the 29s tank water and will let you know if this works. Addition of Vinegar easily brought the level down but adding bicarb just shot alkalinity back up. At the sametime a saturated solution of bicarb only showed a pH of 7.8 (I know it should be close to 9 which would be off the chart)

Sorry to write a book, but that's me.


03/13/2013, 09:42 PM
I didn't know that hot water heaters would add to the alkalinity, although they can cause other problems. That's interesting!

03/13/2013, 09:44 PM
SHORT VERSION: Your hot water heater has a sacrificial (galvanic) electrode made of either Magnesium or Zinc/Aluminum amalgam. These are constantly oxidized to their respective hydroxides. These can increase both alkalinity and pH. So, when doing water changes DO NOT use any hot water.

Unfortunately, I have always tried to match the water temperature. Fortunately, in my main DT the buffering affect of the carbonate system is strong enough to absorb these effects.

Nonetheless, these metals may be detrimental to many and/or all the organisms in the tank and may accumulate if they precipitate.

My LFS store expert told me if I did frequent water changes I wouldn't need a protein skimmer or need to use RO/DI water. I change my water biweekly, religiously. Fortunately, I picked up a protein skimmer and am considering buying an RO/DI unit since I am also setting up dual 55 gallon tanks.

03/13/2013, 09:50 PM
Jonathan, should have specified the alkalinity reading.

Again though, I just filled two 55s with this water. I know I can bring it down with vinegar and then just wait for the buffering capacity of the aragonite to kick in. Since I'm just starting with fish I think I'll leave it alone and let the aragonite and live rock take over.

03/14/2013, 08:40 AM
You mention citric acid... EDTA would be a far better choice for chelation. Especially since you might have zinc in there.

03/14/2013, 01:26 PM

Preaching to the choir man. Sure EDTA is the standard chelant (and I may need to get some) but, I just happened to have some citric acid from the preparation of my ICH medication (trichelated copper, aka Organ-ICK-Cure) that I make and sell locally. $5/bottle, plus shipping, treats 400 gallons, if anyone is interested send me a message.

BTW- I'm a synthetic organic chemist and spent ca. 15 years working on enzyme inhibitors all of which involved binding (though not necessarily chelating) to the enzyme active site metals.

IIRC, EDTA is a non-specific chelant and has a pretty high affinity for most metals. There are some chelants that are specific for certain metals. One of the enzymes I worked on was a zinc metalloprotease. In fact, I got my first patent on this work. Later, I worked on a very unstable protease and we needed specific or weak chelants that would not remove the structural metals (particularly zinc) from the protease (it was not a metalloprotease) so they would be stable. OK, boring, I know. Sorry.

To make it interesting though, zinc is probably the safest of the three metals mentioned in my first post. It is crucial to the growth of any proteinaceous material so it is likely (at low concentrations) to be absorbed and utilized by most tank inhabitants. Aluminum however, is certainly very toxic and Magnesium though quite tame in terms of toxicity, not all that useful biologically (except as Epson salts.)

03/14/2013, 02:30 PM
Oh please stick around. It's good to hear someone speaking my language.

My degree is physical organic, but all of my dissertation work was molecular biology. I worked with ion channel proteins.

The thing with zinc as I understand it is that it is essential in low concentrations, but toxic if elevated. It is a co-factor for so many different enzymes that life would basically be shut down without it. If you worked on metalloproteases then you know exactly what I mean. But at higher levels it starts to interfere with things. And it isn't consumed in any of those reactions so left alone the concentration isn't really going to change over time. At least not from biological action.

It's a lot like copper in that respect. I used to have a really cool article about copper and how the ocean had evolved as a whole to keep the copper level just right. I think it or at least part of it is posted in the sticky copper thread. Turns out that when it comes to metal contaminates, it is often our worst enemies like cyano and dinos that turn out to be our best friends. The main focus of the article was the discovery of copper chelating proteins produced by cyanobacteria and released into the water. They were very long lived proteins and were very well evolved to have just the right equilibrium constant for binding copper so as to keep the free copper concentration in the ocean at exactly the right level. It also said that the total copper in the ocean is something like 100x what the actual needed level is and that these proteins keep 99% of the copper in the ocean locked away but not completely gone so that if copper levels fall, just enough will be released to maintain the needed amount.

Not sure how I got off on that. Maybe the protein chelation talk. Oh well.

The end lesson here, and I think you've already hit on it, is the RODI unit. It gives you that guarantee of good water when it's working right.

03/14/2013, 03:57 PM

Of course my main goal was to get the word out about metals coming from hot water heater electrodes and I still need to figure out how to get his information to the top and/or into Randy Holmes Farley's articles where it needs to be.

Anyway, I even have minor familiarity with Ca channel ions as it relates to heart anti-arrythemia. I knew people who worked on this but never worked on it myself.

As a pseudo-Medicinal Chemist I took a tremendous fascination in molecular biology during the sequencing of the genome. I studied this as it related to biotech stocks (I bought Celera the first day it went public) and just for my own edification. It helped me appreciate some SF stories I was reading by Brian Stableford that were based on molecular biology extrapolations.

I'll be around when I have time. I am setting up a business that will hopefully supplement my investment portfolio enough to allow me to retire and be my own boss.

Best regards,


03/17/2013, 05:58 PM
Since most people use RO/DI it is a non issue. That was my first question Why aren't you using RO/DI? The easy way to fix your ALK problem would be to switch to a salt low in ALK to start with. But that would not get rid of all the metals that are going to be in tap water with or without going through a heater. The average home has steel or copper pipes with lead solder joints. Even if you have a newer home with plastic tubing, the city lines are going to be steel or copper. tap water has also been prove to carry all sorts of other things including hormones and drugs. I would not even consider using tap water myself.