Replacing ARM?

[captexas]

I have a question for those of you with calcium reactors. How often do you replace your reactor media? I had heard a long time ago to change it every 6 months. Just curious what the real world does as mine has been in use for awhile now.

[GaryP]

I've never ran a calcium reactor, but why would you want to replace it? It dissolves when it gets used, right? It seems like you would just want to top it off occasionally.

I'm not being critical, just wondering what it is I'm not taking consideration. Educucate me.

Gary

[Richard]

No need to replace it. I wouldn't just top it off all the time because the sponge filter at the bottom will get clogged eventually.

[GaryP]

How often should it be topped of? I assume there is a point when you reach a critiical point where CO2 contact time is reduced to the point where you need to top off the ARM.

When it gets down to 50%?

Gary

[captexas]

Gary - i'm still not sure about topping off/replacing. I still think there is a point where some of the trace elements that are in the media will be reduced to an insufficient amount. Other than that, I think it is helpful to take the reactor apart every so often to clean the sponge filter and pump. Of course I haven't done that yet. I guess it would take regular testing to tell if the media is losing some of its strength. Since my tank stablized, I don't do much testing unless something strange happens though.

[GaryP]

I wouldn't think the trace minerals would be depleted at a rate faster than the CaCO3. They are trapped inside the matrix of CaCO3 and are released as it is dissolved by the carbonic acid formed by CO2. I don't see how some elements would be selectively solubilized faster than the calcium. If that were the case, you would have a spike in things like Magnesium and Strontium after replacement or top off.

You are right about testing though. Simply running magnesium occasionally would tell you what you need to know. Of course the problem there is that you would baseline data to compare to.

The other question is whether ARM produces enough trace elements to meet the requirements without additional supplements. My gut reaction is yes, since it should be consumed through biological activity at a rate equivalent to the composition of the ARM. You are simply converting dead coral into live coral.

Gary

[astrong]

I have found that the ARM turns to mush after about 12 months. Even when you use a pH controller it still becomes silty mud. Eventually this will hinder circulation. During the year it is fine to top off but I would replace annually. The counter flow designs may be bettter about not clogging but I imagine they will also need replenishing.

I don't add any additional trace elements. There are plenty in the media, food and salt mix. I have found that my magnesium levels are frequently too high, even when everything else I test is fine. The only place it is coming from is the ARM. Shimek discussed trace elements in depth in his articles on toxic tank syndrome. Whether or not you believe the TTS theory he correctly points out that trace elements are best in trace amounts. You really don't need a lot of them to be OK.

[GaryP]

Magnesium is not exactly a trace element. I'm familiar with Shimek's article. What concentration of Magnesium do you consider too high? Mag doesn't have the toxicity characteristics that the heavy metals do.

Gary

[matt]

Chris;

You might think about replacing it when either it gets pretty low in the reactor, like 1/3 full or less, or if you notice any reduction in performance. It will get pretty mushy after a while. You could then take it out, rinse it out, mix it with some new stuff, and re-use it. This way you can clean the reactor if you want, and you won't be throwing out the old ARM. Whether new ARM and old ARM are any different chemically I have no idea. I've heard somewhere that it's not a bad idea to throw out old stuff rather than let it "burn" all the way down, but I have no idea if there's any real reason to do that. The main thing is that the old ARM will have much smaller particles, which can slow the circulation as Astrong says. The mush factor is usually a problem especially with down flow reactors that don't have good strong circulation pumps. Since that was the first one I made, it's down flow, and if I remember the pump is the little eheim. If you want to improve the performance of the reactor, when you clean it, you could try switching around the pump plumbing so that the reactor is working up-flow, and replace the pump with the small 175gph Pan World pressure pump. To switch the pump plumbing, you just need to get some PVC parts- a 1/2" elbow with side outlet works great. The threaded part of that elbow goes to the union at the pump input (close nipple connects them), one of the slip ends goes up, the other goes to the reactor box. The one pointing up, you put in a 1/2"slip by 1/4"thread bushing, then put your CO2 John Guest fitting in there. All my later reactors used that set up, so you could find one to look it over. That piece of plumbing connects to the fitting on the reactor box closest to the center; not the one it's currently connected to. This is what switches the flow from down to up. To be honest, this might or might not increase your efficiency, but changing to the pan world pump definitely will.

Have fun!

[astrong]

Sorry, I didn't mean to imply that Mg was a trace element. I was just trying to say that without additions other levels can be too high while running a Calcium reactor. I believe that calcium reators, water changes and feeding are all that are necessary to keep the levels happy. (Sorry Kent.) I also am limited to testing and don't have any trace test kits, I have Mg but some of the others I let slide. Testing is always a good thing though, they prove that additions and consumption are not always equal, and let you know when to slow down on your supplements.

Everything can have toxicity characteristics though, look at nitrates and phospahtes, they are necessary in small amounts but deadly in high concetrations. Heavy metals have the luxery of letting you know early on. For example gastropods use copper as the center atom of their oyygen transport molecule, hemocyanin, so its important in small levels but copper is deadly to many inverts in higher levels.

I'm not really sure what level of Mg is growth inhibiting, I do know that at higher levels the first problem you will see is solubility competition with other elements. If your Mg is too high you can't dissolve enough Ca, etc. But that works the same with everything. It's also funny that the most two abundant elements Na & Cl are the two least useful. Weird huh?

I looked at my reactor and don't hink I could switch the flow direction with my Eheim 1250 due to space constraints. I could swith to another pump, but I like Eheim so much! I will have to consider if its worth it, I haven't had any problems I couldn't fix by replacing my media annually, but maybe next time, right?

[matt]

I looked at my reactor and don't hink I could switch the flow direction with my Eheim 1250 due to space constraints. I could swith to another pump, but I like Eheim so much! I will have to consider if its worth it, I haven't had any problems I couldn't fix by replacing my media annually, but maybe next time, right?

I was suggesting that Chris (captexas) look into switching flow on his reactor; it's one that I made. I have no idea how this might work on a different reactor. Same thing for pump replacement; I was not referring to anything except "my" reactor.

[captexas]

Thanks Matt, I'm either going to have to get a bigger one or figure out how to lengthen the tube on the one I have sometime soon. I decided that I am going to make my new 240g a reef tank instead of a fish oriented tank and the little reactor of yours I have probably won't be able to keep up.

[Richard]

Why can't you just add a second effluent chamber?

http://www.marinedepot.com/md_viewItem.asp?idproduct=PMCR422-2