Effect of CA reactor size on reactor output

[Wrasse-cal]

All,

I'm curious: sellers rate CA reactors based on tank size. For example Reactor A might be rated for a tank 100-200 gal, whereas Reactor B, which will have a larger chamber and hold more media, will be rated for a tank size 200-300 gal. I'm curious if this is at all relevant.

Generally, all reactor output effluent flows back to the tank through 1/4 inch tube limited to a steady drip. If reactor pH and effluent output rate are the same for Reactor A and B, is there going to be any difference between the functioning of the reactors simply because of chamber size? Is it simply that bigger tanks with higher KH needs will burn through media faster thus the larger chamber so the media does not have to be changed more frequently?

 

[GoVols]

Too me the bubble count and effluent rate maybe tiny, and hard to stay dialed in.
On... a way oversized cal reactor, but I maybe wrong...

Also it's good to change out your media once a year. It gets deep pits, and messes with the internal reactor flow.

@geo
This would be in your wheel house. You guys sized me up, and I know that it's a great long term fit.

Do you have any incite on an "oversized" cal reactor for a smaller reef?

 

[Randy Holmes-Farley Verified Community Expert]

The flow through a larger reactor with more media can be faster than through a smaller reactor with less media. So you get more dissolution over time due to higher water and CO2 flow rates.

The reason is there is more surface area for media to dissolve, and so requires less total contact time between the low pH water and the media.

 

[foxt]

The flow through a larger reactor with more media can be faster than through a smaller reactor with less media. So you get more dissolution over time due to higher water and CO2 flow rates.

The reason is there is more surface area for media to dissolve, and so requires less total contact time between the low pH water and the media.

Since that is true, isn't the alk production rate of a reactor then dependent upon the level of media in the reactor? As the media is consumed, declining surface area available to the water results in declining alk production. Assuming alk demand is constant over this period, I would still need to adjust the reactor (either flow rate, or CO2 rate, or both) to hold the alk production steady. Correct?

 

[Randy Holmes-Farley Verified Community Expert]

Since that is true, isn't the alk production rate of a reactor then dependent upon the level of media in the reactor? As the media is consumed, declining surface area available to the water results in declining alk production. Assuming alk demand is constant over this period, I would still need to adjust the reactor (either flow rate, or CO2 rate, or both) to hold the alk production steady. Correct?

It can be, yes. The surface area may not always be a limiting factor, however. If the incoming pH and flow rate is such that the effluent has reached saturation of dissolved calcium carbonate before it leaves, then more media wouldn't change the effluent.

 

[foxt]

One other point - in my other thread, you've confirmed that alk production can slow down as the level of media in the reactor falls, assuming pH and flow rate are steady. I've been having to lower pH to keep alk steady due to what I thought was increasing demand. I am wondering if what I was really doing was compensating for lower media volume (on both Ca and Mg), and creating a situation where Mg was the limiting factor and it drove up Ca while keeping alk steady? Although my Mg is well above 1400, so I don't see how that could be limiting?