DIY calcium reactor. Single pass or recirculating?

[micagreenmachine]

I've decided to try and build my own calcium reactor. They just look so simple, I couldn't bring myself to buy one for $200!

Anyway, I was doing some research and found this page on single-pass calcium reactors. It made sense to me.... Is there a reason that everyone seems to be using a recirculating reactor or is it just because that's all that's on the market? Is there something wrong with single pass that I don't know about?

Also, using a single pass reactor on a 125 gal. for SPS coral:

1. How much water should be pumped through the reactor?

2. How much CO2 should be added?

3. How much media (aragonite) is needed?

I can always convert a single pass reactor to a recirculating so if I don't get any input, I may just go for it.

Thanks,
~Todd

 

[Anonymous]

hi.
The amount of aragonite is not very important, as long as there is some. The ratio of CO2 and water is anywhere from 1:2 to 1:30, depend on what pH you run your reactor at. The amount depend on your reactor size and your tank size.

Single pass reactor can be less efficient than recirculating ones. Some have problem with high pH, and little Ca dissolution (600ppm or less). Again, it depends on the pH. Recirculating reactor have more controll over the pH, and that's the one single benefit that you need if you have high pH problem.

 

[micagreenmachine]

The way I'm designing it, it will flow from top to bottom. If I drop a pH probe in the top, won't that help me control the pH?

Like I said, if I'm unhappy with the way it works, I can always convert it to recirculate....

Thanks for the input!
~t

 

[Anonymous]

hi.
Do you really mean flow from top to bottom, then exit to the sump? It is a unconventional flow pattern, since some of us who tried this before, found that the calcium medium got so packed (gravity and flow) that nothing flow thru...

Most successfull designs flow from bottom, thru the medium, and to the top. This helps the percolation a lot.

I would just measure the pH exit from the reactor. You don't want the pH probe in there all the time, unless you hook it up to a controller (IMO, a waste of money). pH probe is expensive to replace, and with it in the reactor, I don't know if it will last more than a year... Can anyone confirm this???

If your design is easy to convert to recirculating type, go ahead. I made 8 different reactor designs, and I don't feel any of them is worth upgrading.

 

[Lockart]

If you would like to build your own reactor here is a site with the plans for the one I built.
http://www.animalnetwork.com/fish2/aqfm/1998/mar/features/2/default.asp
It works very well. Here is a picture of it.

 

[micagreenmachine]

Leldon: Wow, that's a nice piece of work! Sounds like it works nice too! If my single pass design donesn't work right, that's about how mine will work after it's converted.

seven ephors: Does the medium really compact up that bad? I figured since I was doing a single pass reactor that the downward flow would be low enough that this wouldn't happen. You're deinitely stirring my mind toward new designs.... Maybe even a reactor that lies on its side instead of upright? Who knows, that's what's cool about doing it yourself! One of us might even invent something worth patenting!

Thanks again for the help,
~Todd

 

[micagreenmachine]

Here's the article that I saw in defense of a single pass reactor design http://www-2.cs.cmu.edu/~cap/raid/careactors/waterfilter/why_single_pass.html

The reason I was going to go for a top down flow were for a few reasons....

1. So if there were any excess CO2 in the reactor, it would stay at the top of the reactor where it could still mix with the water instead of being drawn out.

2. With the water SLOWLY entering at the top of the reactor, the water inside would not be of homogenious pH but would have a gradient, with much lower pH at the top and a much higher pH on the bottom (near the output), allowing only high pH water to exit from the reactor chamber.

3. Having the gradient sounds like a more efficient way to use the CO2, as water that exits the chamber it will have a higher saturation of calcium for the same given amount of CO2 used.


As far as clogging media goes, I'll have to make sure I use a coarse grade of aragonite/crushed coral (I think I have an old bag of crushed coral out in the back yard somewhere. I won't be using a dedicated pump to run the reactor, I'll just T it off of the main pump so I won't have to worry about frying a dedicated pump. The flow thru the reactor will be VERY slow anyway to allow for the pH gradient.

Thanks for bantering with me on this, it keeps my mind open to other ideas and will help me improve on the final design. It will also prompt me to keep in my mind ways of how to build this so if the single-pass top to bottom flow pattern doesn't work, I can easily convert it later for a bottom-up recirculating.

~Todd

 

[Anonymous]

hi.
The medium will compact up pretty well if you circulate the water from top down. Depend on method of water movement, you going to end up with either:
1, spill (overflow, water need to go somewhere else)
2, cloudy tank (aragonite particles being pushed out of the reactor, into the tank
3, damaged pump (high back pressure)
4, malfunction reactor (no output from reactor, but CO2 is still pushed into it)
5, Nothing happened (lucky days)

Regarding hort. reactor chamber, I don't see why anyone would like to do that. Space is important, specially with large sump, skimmer, and all the gadgets under the stands. In addition, there is no advantage in having the reactor chamber laying across, or have the "reverse" flow... Do you have any specific issue that prompt you to come with these methods?

If you look at most DIY reactor plans on the web, they are either the "MKR" style (Leldon's is one), or Sanjay's style. Every one of them work on the same simple principle. Unlike the skimmer, I have not seem any "innovation" in reactor design.

I looked at patent office's database briefly, and found no patent on this matter... any one have input on this?

[ November 14, 2001: Message edited by: seven ephors ]</p>

 

[Anonymous]

hi.
Single pass, reverse flow reactor does has some merits, but if you really think about the alternative, you may want to reconsider.

0, Simplicity is a good virture, but if it cause trouble, it is not a good idea.

1, I use a gas exchange chamber (GXC) to make sure the water is saturated with CO2, and free of gas bubble before enter the aragonite chamber. I may send you a pic if you want to see it. This way, the water will flow from bottom up.

2, depend on flow rate (sounds like *real* slow on your case), the gas exchange may only happen on the interface of the CO2 bubble. The gas does dissolve, but maybe too slow to make any pH gradient more than a few inch deep thru the aragonite bed. The same thing can be acomplish by the use of GXC (faster dissolution rate), and a post aragonite chamber (increase the pH).

3, CO2 is so cheap (less than $10 for 5 lb), the amount used is so little (5 lb is about same amount of CO2 generated by a gallon of gaseline), and the rate is so small (last for months for me when I use it like a brat), that efficiency is not a problem when compare to other possible ramifications.

4, no matter how coarse is your medium, it will turn into paste unless you change the medium every month or something (similar to AragMight/AragMilk that people selling for $10 a pound). But that's with Koralith, Korallin and CaribSea AragMax that I had used. YMMV.

Good luck, and let us know how it turns out.

 

[gbtower]

Just to add a few more thoughts on the subject:

1. A gas reaction chamber is a good idea. If you use a co2 diffuser like the ones used on fw planted tanks, you can skip the needle valve after the co2 regulator. The co2 could be bubbled up a column of water with the water entering through the top, thus giving you the efficient co2 use you had mentioned. This water exiting the bottom of the column would be fed to the bottom of the reaction chamber, giving you the reverse flow benefits mentioned by ck.

2. I'm not sure the ph gradient in the reaction chamber is a more efficient use of the co2. If it was recirculated, then the unused co2 at the exit point would get another chance to react. However, I'm not much of a mathematician so you'd have to crunch out the numbers to figure which way is most efficient. But as ck pointed out, co2 is cheap anyways.

3. I would imagine that the top to bottom flow would eventually plug up the reaction chamber. After some time, even coarse media is reduced to dust. Occasionally (every other month or so), I briefly flush my reactor (reverse flow), and the top of the reaction chamber is filled with milky water even though I also use really coarse coral sand.

Personally, I have used a single pass reverse flow reactor for over a year without any problems. I like the simplicity, and it works.

Have fun with the project.

Gerald

 

[micagreenmachine]

Thanks gbtower,

I was just thinking the exact same thing last night. Should be easy enough to do AND I can make it work with single-pass reverse flow.

Started the initial construction a couple days ago. So far, so good. Hope to be receiving the regulator for the CO2 today.

~t

 

[micagreenmachine]

Well, I finished building the reactor. After talking to some others about this I finally decided on building it as a single-pass with a bottom-up flow. To inject the CO2, I also built a CO2 reactor out of a jar. All of the water flows thru the CO2 reactor before it hits the calcium reactor. I did a test run of it (no media) yesterday and the whole contraption seems to work. I found one really nice thing about designing it like this, I don't have to have a completely leakproof seal for the top of the calcium reactor! It even works with the top off altogether! No CO2 directly enters the reactor, it is all pre-mixed in the CO2 reactor.

I'm going to run it on my existing tank for two weeks, then when I move, I'll move it to my (hopefully constructed by now) 125 gal.

Thanks all for your input! I'll let you all know how it really works in about a month.

~Todd

 

[micagreenmachine]

Here's an update now that it has been in use for 2 months on my old tank (58 gal)...

Wow!

I have to be careful with this thing! After 2 months of use I started getting lazy with testing for calcium. I started noticing the corals looking a bit strange, so I tested and WOW calcium 550 ppm and dkh 16!!! I turned the effluent rate and CO2 WAY down (they were slow before) to try and bring the CA and kh down! 1 week later, 2 pumps siezed because of calcium buildup on the impeller shaft!

I'll continue tweaking and hopefully find stable medium now that it's on a 125.

~t

 

[DJ88]

HI,

I just wanted to add a few things to this thread even though I know you have built yours already Mica. Mainly for anyone concidering building a Ca Reactor so they have a counterpoint to the comments made by Seven.

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote

It is a unconventional flow pattern, since some of us who tried this before, found that the calcium medium got so packed (gravity and flow) that nothing flow thru...

IMO IME not true. It is not an unconverntional flow pattern. I have been running a top down DIY reactor for over a year and a half and have never had the media compress and flow stop. I have found most designs are top down flow and they work very well. All precision marine Ca reactors are top down as are Knop as are a others. I have designed a new Ca reactor for myself this past month and it is once again a "top down" flow pattern. 24" chamber 6"dia.

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote

no matter how coarse is your medium, it will turn into paste unless you change the medium every month or something

Never had mine turn to paste. as well I do not change the media once a month. I filled mine four months ago with ARM and accindentally ran the pH at 6.5 where it did get messy yet my flow never stopped and I didn't replace it all. I went throught 1/2 a chamber in no time tho. If you use ARM you don't need to go as low. I am still getting awesome growth in my tank with my reactor pH at 6.9-7.0.

Once again I wanted to address a few things said that no one put up a counter point to so that someone new has more of a broad base of facts.

If anyone wants to discuss this style of reactor more, feel free to message me.

 

[Ph]

I use homebrew single pass system with no sump, and no dedicated pump. Almost a total passive system

The system gets water from the tank from one port of a PVC manifold that is the main circulation for the tank. From the port it goes to a penplax air valve for water flow control. Then down to a DIY bubble counter-mixing chamber made from a plastic 12 oz Coke bottle. The output of the mixing chamber then goes to the top of 28"x4" PVC tube. The water at PH of 7.0 or so then goes back to the main tank at about a drip a second. Since the water input to the system is slightly pressurized there is enough umph for the return water to make it back up to the main tank. I dose about 1 bubble ever 2 seconds and find that in my 100 gallon even this is a bit hot and I need to throttle back some.

So in conclusion, a single pass system can work very well for what its worth.

HTH

Ph

 

[M.E.Milz]

FWIW, I tend to agree with DJ88's (Darren) comments on the top down flow design. My Precision Marine reactor uses this design and works beautifully. However, it should be noted that I had PM add 4" to height of the 6" diameter reaction chamber (to a total height of 26", I think) and double the size of the Eheim recirculation pump (the 1250, I think). And even though I was using CaribSea's Geo-Marine aragonite (which is not very coarse), the media never compacted. I would guess that this reactor disolves about 2 lbs. of media per month (about 80% of the total media in the chamber was disolved over the past 6 months).

I guess my point is that any design will probably work if you have the right recirculation pump.

[ February 19, 2002: Message edited by: M.E.Milz ]</p>

 

[Anonymous]

hi.


I agree with MEM and Darren. In one of my post, I said YMMV, and that's exactly what I meant. I guess I was a little too strong in my statement, and make it sounds like there is no other way.

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote

I guess my point is that any design will probably work if you have the right recirculation pump.

I always use Maxijet 1200 in all my DIY reactors, and that's maybe why I have problem with compaction of media.

 

[micagreenmachine]

FWIW,

I think the "key" to a single-pass reactor is to have a CO2 reactor as the input. That way, you've dropped the pH before the water even enters the chamber. When my calcium went off the scale, I was only adding CO2 at a rate of 1 1/2 bubbles per second and had an efluent rate of a slight trickle. Since then, I've reduced it to 1 bubble every 2 seconds and a constant drip for the effluent. Hopefully, that should do it.

Thanks all for the input, it made me think before I commited the work to glue and PVC. And, if I'm not satisfied with my design, I can always turn it into a recirculating-type with one more hole and a pump!

~t

 

[fishpoo]

that's beautiful work DJ88. I was wondering how tall your reactor is and do you plan on using a second chamber.

 

[DJ88]

Hey fishpoo,

The reaction chamber is 24" high, and it's 6" diameter tubing. It holds 16 lbs of ARM media.

This is going to be it. No second chamber. I am only putting this on a 45 gallon system. yeah 45 gallons.

Due to the following reasons I am not forseeing the need for a second chamber;

<ul type="square">[*]Very slow effluent flow rate due to tank size/demand(currently about 90ml/min on my 33 gallon tank). This will change as demand goes up.[*]Low CO2 useage due to the CO2 recirculation line. I am expecting a bubble rate in the neighbourhood of 30/min.[*]Lower Co2 useage due to the increased water volume within the reactor. Due to the higher stability of the H2O in the reactor once the pH in the reactor is at 6.8-6.9 I will not need to use as much CO2 to keep it at the lower pH as a smaller volume reactor does. This will change once again as demand in the tank goes up. [*]Dwell time in the reactor due to a larger reaction chamber will increase the time for the CO2 to react with the media.
[/list]

I have also been doing some looking into second chambers and feel that once you get your flow rate up to any great amount you will force the water in the second chamber to go around the media in the second chamber and not through the media itself. The effluent would rather find the easiest route out and next to the tubing is a smooth laminar area insted of the convoluted path through the media.

I have looked into this on higher demand systems that are running an effluent rate of 100ml/min or greater and have found that in most cases the pH out of the second chamber was at the most .2 different from the main chamber. So if that is the case, any excess CO2 is not being used up due to lack of contact time. One solution to remedy this is to make a taller and narrower second chamber to force the effluent through. That will give it more time to touch the media close to the wall of the tubing and let any excess CO2 in solution react with the media and dissolve it. Another solution is to put a recirculating pump on the second chamber and do the same as the first. Without a CO2 injection. By recirculating it yuou will force it through the media and this will give it the time needed to dissolve. By doing this in a high effluent demand system I can see a more significant drop in effluent pH happening.

I don't know if this was more than you were expecting.. But there it is..

Any questions, go ahead and ask.

[ February 27, 2002: Message edited by: DJ88 ]</p>