Calcium Reactor vs. Automated Dosing Pumps

[+Mitch]

You could use your Apex controller you have to set it up. One day maybe I'll get a 2nd pH probe and modify the cap of the reactor to hold the probe, but for now one pH probe works for me. I just program my Apex to shut off the CO2 solenoid if my pH gets below a certain number.

I have my CaRx CO2 controlled with an Apex and have 2 pH probes (one for the effluent, the other as a fail-safe measuring the DT). About this time last year, my CaRx effluent pH probe went bad reading high, so too much CO2 was injected and melted the media. I did not find that the DT pH was affected by this. I do have the effluent drip where the return/protein skimmer is so excess CO2 can be removed. I neglected to measure Ca, Alk, and Mg at that time, so don't know in this regard.

Personally, I wanted to minimize the maintenance of owning a reef tank, as long as I had appropriate safe-guards. Reasonable up front investment in equipment was ok, so I think a CaRx, a controller, dual pH probes, etc are must haves to not be a slave to your tank.

[victoly]

what size was your DT?

[subsea]

This is just a simple price comparison for 100 gallon tank

http://www.bulkreefs...eactor-418.html - $299.99 for the reactor

http://www.bulkreefs...-regulator.html $94.99 for the regulator

http://www.bulkreefs...tank-5-lbs.html $79.99 for the tank

http://www.google.co...UwAA#scoring=tp pH controller $95.38

Consumables Cost (annual)

http://www.marinedep...-FICRCM-vi.html $22.99 * 2 uses/yr = 45.98

CO2 - $30

Total for CO2 = $646.33 for the first yea!yr of operation. This cost does not include incidentals like tubing/plumbing for setup OR shipping/taxes for goods. Total cost would probably be somewhere around $700.

I built my own reactor for less than $50 out of 4" PVC. I ran my system on manual, which means one less thing to fail, a pH controller. I had an extended system that including 500G of refugiums, growout troughs and 150G display tank. I had oppossite photoperiods and had no problems with pH stability. Initialy there was much testing and adjusting for several weeks. Once calcium was slected as the concentration to monitor, there was no more tweaking required. Maintenance required was twice a year at less than one hour of labor in one year. When you put the labor cost in the equation, calcium reactor wins, imo.

I thought the thread was going to deal with failure analysys. Worst case sceanario.

Patrick

You are running a special case tank which is heavily dominated by CO2 sinks. Most people don't have the capacity to safely absorb the quantity of gas that could potentially leak out of a system that doesn't have timer/pH control. However, your point about labor cost is totally valid. When you amortize your "time spent" mixing solution, over the life of your tank, it might very well be worth the extra couple bucks in startup cost if safety isn't a driving factor.

What is a CO2 sink?

Nbuffering assume that because of no timer or pH controller, I have no control. I use a metering needle valve to set CO2 flow rate. If it fails, it would fail closed and block CO2. Worst case scenario would be low calcium and alkalinity.

If the timer on your dosing pump fails closed, you will empty your batch tank into your reef tank. That does not sound like "best practice" to me.

CO2 sink meaning a large consumer of CO2. All of the caulerpa that you have, in addition to the large tank volume, gives you a much wider cushion than the joe blow hobbyist. I have had a solenoid on a CO2 tank fail and nuke a previous tank, so it is possible to have mechanical failure on a CO2 based system.

Victory, I do not use either dosing or a calcium reactor in my display tank. I use DSB with alkalinity buffering facilitated with aroggonite in the "facultative zone". In my seaweed grow out tanks, I use degassing columns with a water flow rate of 80 GPM to provide for CO2 gas exchange. There is more than one good way to do this job.

Have fun with the thread,

Patrick