Kalk reactor help, kalk not lasting more than a few days

j0tca · #1 01/11/2007, 05:13 PM

Hi,

I recently built my own kalk reactor and haven't ben able to get it working properly. My effluent comes out at 12.3 when I first add the kalk powder but after the first week, the effluent is down to 11.9, indicating not true kalkwasser.

I have a mixing pump that mixes it 15 minutes, an hour before I add it to the tank.

My question is, why does my kalk reactor lose it's potency so fast. I've read of kalk reactors online here that only need to be refilled every 3 months. I'm assuming I have too much air/water interchange somehow and the co2 in the air is reacting with the limewater, turning it to calcium carbonate. My reactor is sealed except for the outlet pipe (1/4") and the inlet pipe (1/4") which comes from my ro/di. My water coming in seems to occasionally have air bubbles in it, and I can't figure out why. Do all RO/DI systems allow some air in?

because of the air coming in, I have my water coming into a small (1/4) open pipeso that air excapes back up the pipe and into open air. I estimate my reactor's capacity is 10 gallons so is this 1/4" opening really allowing enough co2 in to ruin my kalkwasser?

Anyone here have an idea if I have to seal it completely?

what about creating some sort of co2 scrubber for the incoming water? If I seal my reactor and scrub out the co2 that would dramatically increase the life of my kalkwasser inside the reactor, anyone know a way to do this?

Thanks for the help,
Will

douggiestyle · #2 01/11/2007, 07:03 PM

im not familiar with your figures on kalk ph. where did you get them? a link would be great.

j0tca · #3 01/11/2007, 10:20 PM

Saturated Kalkwasser has a ph of 12.4 to 12.5 depending on the temperature. I can't right now remember what it is at 80 degrees but it's easy to test, just saturate some water

I normally get an efluant of aroun 8.37 when my reactor is working properly. Because of the nature of the pH scale (exponential) Kalkwasser at pH of 12 is about 1/2 the potency of saturated solution. There are many links to this subject on the web, it's not wirht repeating them here but just google "saturated Kalkwasser" and it will help you start.

HTH,

Will

natual · #4 01/12/2007, 12:50 AM

You will get bubbles in the line when it changes temp or sits for a while. Remember you are using purified water not degassed water so some CO2 is entering with RO water.

BTW cold water can hold much more CO2 than room temp. So when water heats up it will lose it ablitity to 'store' air, hence the bubbles.
Just minimize contact of your water with the air prior to the effluent line.
Temperature is probably the key.

Donw · #5 01/12/2007, 12:13 PM

If this thing is connected directly to a rodi, the di resin removes any uncharged particles including co2. Assuming your effluent line is the 1/4 line you mentioned. If this is submerged you should have no air in the reactor. The easiest way to tell is just dont stir and see if the kalk forms a skim on top. If it does then your pulling in air. If no skin then you can look at the calk or even the stirring method.
The ph of the effluent should be 12+.

Don

RichConley · #6 01/12/2007, 02:59 PM

Quote:

Originally posted by Donw
If this thing is connected directly to a rodi, the di resin removes any uncharged particles including co2.

No, DI removes charged particles.

Donw · #7 01/12/2007, 03:19 PM

Quote:

Originally posted by RichConley
No, DI removes charged particles.

Yes, my old age is showing again. CRS

Don

j0tca · #8 01/12/2007, 07:53 PM

thanks alot for the help guys,

Donw,

That's a great tip looking for a skim in the reactor, I've always tried to ensure there is no air at all so I couldn't tell if a skim was being formed, by sealing it with a little ait in it, I can tell if new CO2 is coming in.

So, does the resin remove CO2?

Perhaps it's worth putting a resevoir with a heater in it before the RO/DI with a one way valve. Do you guys have any idea what the ability of water to store CO2 is compared to temperature, I mean, if we bring the water to 85 degrees C, will all gas be expunged?

Will

AcroSteve · #9 01/12/2007, 10:04 PM

I would say 11.9 is not too bad. But you should get a conductivity meter to get a better measurement of the saturation level.

j0tca · #10 01/12/2007, 10:10 PM

umm... there is no better measure of the saturation than pH. It is very precise if you look up the temperature comparrison. 11.9 is actually very bad, it indicates about 1/2 saturation. The pH scale is exponential so a drop of 1 is actually a drop of 10X, a drop of .4 is about 2x if I recall although I can't seem to find my calculator to double check.

HTH,
Will

mc-cro · #11 01/13/2007, 01:21 PM

I have never heard anyone check the saturation level of kalk reactors. I have always assumed, as long as there is still powder in the bottom, with regular mixing, then it is saturated.

for the record, I usually add powder to my reactor weekly. about those reactors that "have read going for 3 months", I seriously doubt that anyone has checked the ph.......they are probably thinking the same as me, if there powder in the bottom, its saturated.

AcroSteve · #12 01/13/2007, 03:15 PM

umm... Check it out

Conductivity is the way to go for accuracy.
http://archive.reefcentral.com/forum...hreadid=943841

Or at least this Randy guy thinks so.

douggiestyle · #13 01/13/2007, 04:46 PM

thanks for clearing that up steve. i appreciate the link.

j0tca · #14 01/14/2007, 05:47 PM

Yup, I'm wrong, it seems conductivity is a far better measure, thanks for the link.

mc, if there is gas exchange with air, much of the powder at the bottom of a reactor will be calcium carbonate, the result of calcium ions encountering carbonic acid in the water. Calcium carbonate is the end result of what we're trying to do with kalk addition, it's what coral skeletons are made from but is essentially insolule in water.

Does anyone know if an ro/di removes co2?

AcroSteve · #15 01/14/2007, 06:52 PM

I think it does.

jdieck · #16 01/20/2007, 03:13 AM

Quote:

Originally posted by j0tca

Does anyone know if an ro/di removes co2?

If you have an anion cartridge it will.
Mixed bed resins contain Anion resins also so it will remove it.
When there is high concentration of CO2 in the water it will be very noticeable as the life of the cartridge is reduced significantly.

Another thing you could try is to install a DIY PVC "Cartridge" filled with aragonite sand or ARM media on the water line to the reactor, that might help as a CO2 scrubber in case the water in the reservoir is uptaking a lot of CO2 from the air.