phosphate & calcium reactors

[VictorE]

As I continue my construction/design of my tank, I've been told that a substrate reactor for removal of phosphates would be appropriate for this 300 gallon system.

Question: Can I put this additional reactor in series with the calcium reactor, fed off the same return line (and flow rate), or does the phosphate reactor require different flow rates and feeds than the calcium reactor?

[Shane Hoffman]

Different flows are required. You will need to adjust your flow through phosphate reactor to a very precise setting in order to produce the necessary "tumbling action" required for the gfo to be efficient.

[bertoni]

I agree. Separate pumps would be far better.

[VictorE]

So I see that everyone here agrees that these should be plumbed in parallel rather than in series. The proposed feed line for these reactors is 1/2 of the 1500 gallons per hour (branched off from chiller).

So next question: First, will 750 gallons per hour be enough for this tumbling effect outlined above? Second, does the discharge from a phosphate reactor go into the sump justlike the calcium reactor?

The calcium reactor I purchased from Pracision Marine has its own little pump (recirculation?), but the phosphate reactor seems not to have this small recirculation pump. Am I missing something with regards as to how this phopshate reactor works?

[der_wille_zur_macht]

The phosphate reactor is basically just a container to hold media so you can pump water through it. There's no real magic other than getting the flow rate correct, and most do not come with pumps (many people run them from a T on the return line, or other sources).

Meanwhile, calcium reactors are a little more complicated, and typically utilize a recirculation pump to keep acidic water moving through the media. Then, a rather small pump (or other water supply) is fed into it, to pass tank water through at a typically very low flow rate. Fine adjustment of this flow rate can be very important (in addition to adjustment of the rate CO2 is being added to the reactor) to get the right dosing rate for the tank, without overwhelming the reactor and melting the media.

If you can post the model and manufacturer of the phosphate reactor you have, we can make better suggestions on how to supply it.

[VictorE]

So the output from the phosphate reactor goes directly into the sump?

I'm thinking one of Precision Marine's reactors (http://www.precisionmarine.com/html/...e_reactor.html)

Is a bigger reactor better by way of not having to replace the media as often? Would this size issue apply to the calcium reactor as well?

[Shane Hoffman]

I have a pump that is only capable of 250gph and it has to be throttled back just a little bit to aquire the correct tumbling action. IMO 750gph would be way to much. You wont need a larger reactor. I use GFO from BRS. It has instructions as far as how much to use per gallon. What ever media you use should come with instructions. Yes the output should discharge into the sump.

[der_wille_zur_macht]

Originally Posted by VictorE

So the output from the phosphate reactor goes directly into the sump?

Yes.

Is a bigger reactor better by way of not having to replace the media as often? Would this size issue apply to the calcium reactor as well?

Generally no. Think of the amount of media as influencing removal rate as well as removal capacity. Too much media and the tank will get sucked totally dry of phosphates - which might sound good, but can be dangerous, since most corals need a tiny (undetectably small) amount of phosphate in the water. Hence, if you're going with a reputable manufacturer like PM, stick with their suggestion for tank sizing.

With a calcium reactor, size influences operation beyond just as a strict correlation to tank size. Unfortunately, the style of reactor (single stage, two stage, dimensions, how effective the spraybar or diffuser is, etc.) plays a role too, so it's hard to talk in generalizations.

Think of it this way - in a media (i.e. GFO) reactor, you are simply pushing tank water through some media and hoping that the media absorbs something from the water. With a calcium reactor, you are slowly passing tank water through a nearly-closed recirculating loop that introduces and dissolves CO2 to create an acidic environment to dissolve calcium carbonate media. In the case of the phosphate reactor, you're more or less using brute force to push water past media and remove something from the water. With a Ca reactor, you're creating a delicate environment to dissolve media, then slowly introducing the resultant solution into your tank. It's probably a shame that the term "reactor" is applied to both, since they're vastly different processes.

[VictorE]

What is GFO an abbreviation of?

[der_wille_zur_macht]

Granular ferric oxide. Think of it as carefully made rust.

[VictorE]

Thanks!

So "rust" removes phosphates and carbon generally clears the water.

I've been told that I should not put a reactor in this system with carbon as it is only used in certain circumstances. First, how frequently are reefers typically having to add a bag of carbon in the sump? What does carbon remove and what does it do to a reef tank if used improperly.

Second, how often does the GFO media have to be replaced? I'm sure it depends on the phosphate concentration, but what is a good rule of thumb or expectation?

[fatdaddy]

Originally Posted by VictorE

So "rust" removes phosphates

It's actually ferrous hydroxide (not ferrous oxide), so not rust although there is probably some in the preparation.

[der_wille_zur_macht]

Do you have a reference that supports that? Every time I've seen "GFO" used to describe the media we use for phosphate control, it's been in reference to oxide, as seen in product marketing material and sometimes on the products themselves:

http://www.bulkreefsupply.com/store/...sphate-remover

I know GFH (granular ferric hydroxide) is sometimes used in the treatment of water and wastewater to remove arsenic, but I don't know of it's use in the marine aquarium hobby.

[fatdaddy]

Originally Posted by der_wille_zur_macht

Do you have a reference that supports that?

I'll hunt tonight. Perhaps, I'm in error.

[VictorE]

But back to the carbon use issue and frequency of GFO replacement. What are everyone's thoughts?

[fatdaddy]

Originally Posted by VictorE

But back to the carbon use issue and frequency of GFO replacement. What are everyone's thoughts?

I use carbon all the time as it keeps the water nice and clear. You'll notice your water yellowing when the carbon runs out.

However, if you're doing large water changes, then I think you can avoid carbon. I currently have 500g in the system, so I only do a 10% water change 1/month.

Negs on carbon: dust is bad for the fish gills. However, after loading a reactor just run with RO/DI water until clear. (Or, do it as part of a water change and put waste water into a bucket until clear.)

Re: GFO - I would *not* replace unless your monthly surveillance test detects an increase. That stuff is expensive, and the idea isn't to rip out all the phosphate, but just the excess.

Also, growing Chaeto is a good phosphate remover too. I'm overdue for a change, but I now have chaeto growing and I'm hoping that will be sufficient. So far, phosphates have flat lined at zero.

[VictorE]

So, you're the first to tell me that carbon reactors in these systems are acceptable. So far, two people (a large speciality aquarium retailer and Bulk Reef Supply) have told me thisi s a bad idea. The suggestion has been to put carbon in the sump only under circumstances for a short period of time.

So now I'm completely confused on the plusses and minuses of setting up an additional reactor with carbon.

[fatdaddy]

Originally Posted by VictorE

So, you're the first to tell me that carbon reactors in these systems are acceptable. So far, two people (a large speciality aquarium retailer and Bulk Reef Supply) have told me thisi s a bad idea. The suggestion has been to put carbon in the sump only under circumstances for a short period of time.

So now I'm completely confused on the plusses and minuses of setting up an additional reactor with carbon.

Ha! Yeah, you'll get plenty of opinions. Usually the larger systems on the low end of water changes run carbon. Smaller systems can usually get away with just water changes to keep things clear.

Just remember to make changes .... slowly. I once had a tank that yellowed because I was using carbon for fresh water. I kept changing and changing until I finally bought a different (and correct) kind, and it went from yellow to crystal clear overnight. Not cool.

Plus-side: clear water as the carbon binds to organics that will make your water look yellow (gelbstuff). Also, it will pick up metals that are dangerous to fish such as copper.

Neg-Side: something else to buy, maintain, etc. Carbon dust is bad for your fish.

Just be consistent in what you do.

[der_wille_zur_macht]

Originally Posted by fatdaddy

Just be consistent in what you do.

And do your best to understand the justifications, advantages, disadvantages, etc. for anything you do - vs. taking advice from an LFS or us blindly.

+1 on fatdaddy's comments regarding carbon and GFO, BTW.

[fatdaddy]

Originally Posted by der_wille_zur_macht

Do you have a reference that supports that? Every time I've seen "GFO" used to describe the media we use for phosphate control, it's been in reference to oxide,

Okay, I dug out my phosban and it says: "Synthetic ferric oxide hydroxide".

BuckeyFieldSupply has: Ferric Hydroxide
http://www.buckeyefieldsupply.com/sh...owspecials=124

btw, I bought a bucket of the water treatment ferrous hydroxide used for arsenic. I worked fine although it was wet and leached iron so I had to run a considerable amount of water through it before putting it in the system.

Perhaps both work?

[der_wille_zur_macht]

Fascinating. I'm no chemist so I won't comment on the interchangeability of the two products.

[frewd]

go to bulkreefsupply or someplace and get one of there dual reactors for 50$ and a maxijet and run both gfo and carbon.