Dosing Pumps & Calcium Reactors Explained for Reef Tanks
Dosing pumps and calcium reactors are popular tools for maintaining the balance of key parameters that corals need—especially calcium (Ca), alkalinity (often measured as dKH), and carbonate/bicarbonate levels. When these drift, growth can slow and sensitive species may struggle. While both approaches can support stable reef systems, they differ significantly in how they deliver supplements and how they’re tuned. What dosing pumps do A dosing pump is a controlled dosing system that delive... Read more »
Dosing Systems Explained: Two-Part, Calcium Reactor, and Balling
Maintaining balanced calcium and alkalinity is a cornerstone of reef tank stability, especially in systems with fast-growing corals or high-demand livestock. While many approaches exist, three methods show up most often in hobbyist setups: two-part dosing, calcium reactors, and balling. Though they all target the same chemical goal—supporting coral calcification—they differ in how they deliver ions, how they’re monitored, and how much automation (or manual work) they require. Two-part do... Read more »
Choosing between a calcium reactor and two-part dosing is one of the most important decisions for reef aquariums—because the right method helps keep calcium and alkalinity stable, supporting coral growth and preventing slow chemistry drift. Both approaches can work well, but they suit different systems and lifestyles. The best choice depends on your tank’s demand, how hands-on you want to be, and how comfortable you are with equipment tuning versus routine measurement. How each system de... Read more »
Two-Part Dosing Systems and Calcium Reactors Explained
Maintaining calcium and alkalinity is one of the central challenges in reef-keeping. Corals use these minerals to build skeletons, and rapid swings can slow growth or stress sensitive organisms. Two of the most widely used strategies are two-part dosing systems and calcium reactors. While both aim to deliver the same essentials, they do it in different ways—and that difference affects how you set up, calibrate, and maintain your system. Two-part dosing typically supplies calcium and alkalinity ... Read more »
I saw a koi guy that made giant filter media reactors out of 5g buckets. he’d put a bulkhead in the lid and another (offset) in the bottom, run the pipes internally past each other so the water had to move from the lid, to (almost) the bottom of the bucket, then up through the media to the other pipe opening, then fall down through the bottom bulkhead and back to the koi tank.
I’m thinking of an alternative for a giant calcium reactor.
Materials
1x - 5g bucket and a really tight lid (like this one)
1x - 4″ (or so) diameter of acrylic tube, or a 4″ square acrylic box. anything water-tight and reef-safe will do fine, but clear is best. Add a bottom to this with weld-on or similar -- no top on this.
1x - venturi pump and CO2 setup (recommend a pH-controlled CO2 source)
2x - pvc bulkheads appropriate to the pump, maybe 1/2″ or 3/4″. One extra o-ring/seal for the bulkhead, or lots of silicone is probably fine.one for the effluent
2x - Airline bulkheads. one with airline on both sides, the other one-sided
4ft of airline for CO2 recirculation needs, plus length from CO2 tank to venturi (through controller) and enough length to get the effluent to the destination (the fuge for me)
Misc PVC pipe for recirculation, airline for inlet/effluent, probably other things
2 low profile screens that screw/slip into the bulkheads and keep the media out of the pump.
TBD screen material to sit on the acrylic tube. I might use a thin sheet of acrylic with drilled holes
Manifold outlet for source water (with gate/needle valve) or a standalone pump for the same.
Basic idea
connect the outlet of the venturi pump to a bulkhead near the edge on the bottom of the bucket with no pipe inside the bucket.
Put the acrylic tube in the middle of the bucket, so the covered base is against the bottom of the bucket. the acrylic tube should go most of the way up the bucket, but not quite to the top
Connect the acrylic tube with a bulkhead so one o-ring is between the bulkhead and the acrylic, the other between the acrylic and the bucket. (you could pile silicone under the acrylic instead of the extra o-ring if desired).This bulkhead leads to the venturi pump’s inlet for recirculation of the acidic water.
Connect the CO2 source to the venturi
Tee in the tank water source (ie, manifold) to the inlet of the venturi pump, as it comes from the bucket’s recirculation output. Make sure there’s a fine-adjustment valve before the tank water enters the line.
Put one screen about an inch up from the bottom outside the acrylic tube and another about the same height inside the acrylic tube (the media sits on thise)
Optionally put another screen sitting on the top of the acrylic tube with holes all over so water can escape the outside and enter the inside, but the media stays in place. This can easily be held in place with a few scraps of acrylic adhered to the lid that are the right height to push this top screen down against the acrylic tube.
Put the effluent bulkhead in the lid of the bucket. Run a small piece of airline under the lid (above the screen/media level) so this doesn’t suck trapped CO2 off the top of the bucket. 1/2″ is probably plenty. Run the outide of this bulkhead via airline to your effluent location (for me: the fuge)
Put the second airline bulkhead on the lid with minimal insertion into the lid so it pulls any trapped CO2 off the top.this airline runs back down to the inlet of the venturi pump so any excess CO2 that builds up at the top of the reactor gets sucked back into the venturi for re-use.
note: the effluent line is left open w/o restriction in this idea, which means the reactor operates with no real pressure. you could add a valve on the outlet to force some pressure, but it makes sense to me to throttle the input water, not the output. Also, this means it should purge pretty well when starting up, the effluent line will just blow out a bunch of air until it’s filled up. you could add another purge valve if you prefer.
Run the effluent to some kind of box so the pH can be monitored there, or add a fitting to the lid of the bucket so a pH probe can be there.
This up-then-down design is a bit more complicated (you could leave out the acrylic tube and just have a standpipe in the middle bulkhead instead), but I think it gives real advantages because the media should have faster water movement, which should keep things more even. Also the pump plumbing is very short, which is nifty. I do wonder about just putting the recirculation intake in the lid with a giant pile of media in the bucket, then there might not be need for the separate CO2 recirculation, but I’m not sure the trapped air would really get pushed through the larger pipe, so I think this is better.
Changing media and cleaning
Turn off the CO2 source and close the inlet from the manifold
optional: pop the effluent out of the bulkhead to get it out of the way
Unscrew lid, optional: put a slip-fit (or loosely applied threaded) plug in the standpipe if you want
note: adding unions between the bulkheads and recirculation pump as well as between the manifold and the reactor would make this easier. This way, the whole bucket/reactor can be removed for cleaning, and the pump removed from the reactor to clean it.
pull the bottom screen out to clean it, also clean the top screen
replace bottom screen, pour in media, replace top screen
optional: Fill bucket with tank water (just speeds up the re-start and saves the pump from running mostly-dry at first, also lets you leave the
screw on lid, replace effluent line, turn on inlet from manifold and CO2 source
Basic function
Water gets trickled into the inlet bulkhead via the needle valve on the manifold, which enters the recirculating flow that goes in the non-standpipe bulkhead, flows up through the media (and screens), then gets pulled down the standpipe into the venturi pump for recirculation.
As CO2 is dosed in via the controller, the venturi mixes the CO2 into the recirculating water, which then re-enters the bucket (reactor).
As more water is allowed into the system from the manifold, the bucket fills up until it hits the lid, then it’s pushed out the effluent bulkhead and through the effluent line. If the effluent line never raises much above the lid (say, an elbow fitting and down to the sump), then there’s virtually no pressure on the system and nothing to worry about. I want to run the effluent up to an elevated fuge, so I’ll have to be thoughtful about making sure the bulkheads and lid are very tight-fitting. Or I might actually put the reactor in the fuge and run the manifold line up to the reactor.
Of course, you can’t see the media, so you’d have to either check periodically, or be quick to notice when the alkalinity/Ca is dropping in the tank. I suppose I could find a clear bucket?
TBD
I know I’m missing something for a bubble counter situation, and the pH controller/solenoid setup is missing. Presumably, I’ll choose something that lets me set the target pH from the reef-pi and set the bubble counter so it can’t push the media much below 6.6 as a safety net.
Best of all would be to wire something like the AM pinpoint probes for Calcium and Alkilinity to my reef-pi, then I can have continuous monitoring of those values and have the target pH adjusted accordingly (if Ca/Alk rise above my target, move the pH up; if they fall below my target, move the pH down). I think I’ll tend toward the perspective to keep the flow rate relatively high; this will consume a little more CO2 (as it doesn’t all get used before becoming effluent), but that CO2 will be headed to the fuge, so I think it’s mostly a win, and it should stave off issues with overly-melted media crudding things up because of the higher flow rate and the relatively-higher pH it would be running (to achieve the same Ca/Alk ‘dose’ per hour)
The fun part
This probably holds about 4g of media...for most people, that’s about the same as the SRO CR5000D The manufacturer suggests it is good for a 400-600g system, other places say it’s good for 700-1000g...not too shabby. of course you could do this with a different dimension bucket for more/less capacity, but if you have the space, a 5g bucket is just too easy. You could also add a second bucket with uniseals to join the two, one bulkhead each for an 8g capacity. Recirculates from the bottom of one to the bottom of the other. put the effluent bulkhead on the bottom of the second one, run the line above the lids so it doesn’t drain until they are full. But unless you’re worried about CO2 in the effluent, that just seems overkill.
I haven’t priced it out, but I’m thinking everything other than the pump will cost around $100, maybe $150. Even if I spend $300 on the pump (seems unlikely), this thing costs about half of the price for a similar capacity reactor. and it seems like it’ll be pretty easy to make and pretty easy to add media.
Calcium Reactor UltraReef UCS 140 - review - Finally we can talk about the calcium reactor UltraReef UCS 140, suggested by the builder for aquariums until 500 liters, and tested in my reef aquarium of more or less 400 liters. This article is also available in: italiano The reactor is equipped with just one pump, the Sicce Syncra 2.0...
Un nuovo articolo su http://www.danireef.com/2019/02/06/calcium-reactor-ultrareef-ucs-140-review/
Lots of people would like to own an aquarium in their home and are attracted by the thought of owning some of the more exotic species of fish. What puts most people off, however, is the possible cost of all the equipment needed. What might seem to be a relatively inexpensive pet, needing only a tank, a filter, a light, and some fish, can begin to seem more pricey when taking into consideration water treatments and tests, protein skimmers, and CALCIUM REACTORS
Photo by ctenophore
But do you actually require a calcium reactor? Just what is a calcium reactor anyway? Is it really so important? The first piece of advice I should offer is to not be scared by the various aquarium supplies available. The large amount of technology being sold might seem huge at first but remember that you don't really need all of this additional equipment. Be sensible, do some research into each item and determine whether you do need their help to keep the environment in your aquarium clean. Secondly - calcium reactors. So just what is a calcium reactor?
A calcium reactor is a piece of aquarium equipment designed to keep the level of calcium in your water high. This is especially useful if there is a particular drain on calcium levels in the aquarium. A lack of calcium can occur when there are several saltwater fish in a tank but is more often caused by placing a reef in the tank with them. For those with reef tanks it is crucial to have a calcium reactor. Most species of fish are vulnerable to fluctuating calcium levels and will be badly effected if the calcium content reaches a certain level.
Additional costs such as calcium reactors will certainly increase the overall cost of an aquarium. However, it is important to see that they can also provide you with the ability to keep more exotic and diverse tanks. Anyone can create a basic fresh water aquarium, but a diverse marine tank including coral life is far more complex and impressive, and also a challenge to maintain correctly.
So rather than focusing on the costs of such a challenge think of what an opportunity you will be giving yourself. But don't stress; you shouldn't need to buy a calcium reactor immediately. In fact it should be several weeks, before the calcium in the tank will need to be altered. Only when you've populated your tank fully will it become necessary.
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