Kalk Dosing

[NaCl_H2O]

OK, I read the article in Don-n-SA's post (http://www.maast.org/index.php?name=PNphpBB2&file=viewtopic&t=8915), a very good article! But it got me thinking about my Kalk dosing, which isn't going as well as I would like.

BTW - JimD, please chime in since you started all this :-D

I have built a Kalk Reactor, and I think it is working very well (at least as designed), but I think I am spitting into a lake! I have a system with 700+g of capacity, and what I have estimated as 400-500g of actual water volume/circulation. I believe I am topping off 5-10g/day of fresh water (Kalk water now) and the itty-bitty dosing pump runs most of the day. The Kalk "Mixing" occurs a few times overnight in 15-30 min intervals, the mixer shuts off at 5:00am, and the dosing pump/top off starts at 7:00am.

Originally, my parameters looked great (PH, etc.) but are now dropping off somewhat and the dosing pump isn't keeping up with the top off requirement. Bottom line, I don't believe the reactor has the needed volume and the dosing pump is "undersized".

So ... I am considering the following - let me know what you think?

My RO/DI resovoir is about 20g, and originally had a MAG2 connected to the top off system when I wasn't dosing Kalkwater. Typically, the top off system would come on and dump about .25 - 1.0 g of water into the sump before shutting off, and this would happen once every hour or two.

I am considering running the dosing pump from the Kalk reactor "Back" to the RO/DI resovoir and re-installing the MAG2 as the top off pump.
- RO/DI -> Resovoir -> Dosing pump -> Kalk Reactor,
- Pressure into Reactor from Dosing pump forces clear Kalk Water back into Resovoir
- Top Off/MAG2 pulls Kalkwater from resovoir

Initially, I would not have a very saturated Kalk mixture in the resovoir, but after a few days I assume it would reach the saturation level? I will most likely need to mess with my mix/dose cycles to get enough Kalk flowing back into the resovoir?

According to the article, dumping in 1.25% of total aquarium volume in Limewater all at once is "Too Much", but dosing 0.25% is a "safe" level. Given my volume, 0.25% would be about 1g, so the topoff/MAG2 levels of .25 - 1.0g at a time should be "safe".

Hope this makes some sense? Let me know what you think????

Thx - Steve

[Tim Marvin]

I would do exactly what you are thinking Steve. I dose a lot of Kalk and have great growth on everything from corals to coralline.

[JimD]

"Scratchin my head" Im not quite sure I understand but, like I said in one of my emails, I thought a reactor of this size may not keep up with your demand because of the overall water volume., the volume in the chamber is in the 1-1.5 gallon range depending on how tall it is. If you mix/settle for two hours four times a day = eight hours, leaving sixteen hours of dosing time, find out how much the pump doses per day and compare that to your evaporation rate and youll know the output rate for the pump you need. You might try a plumbing supply house to see if they have larger diameter pvc like 8-10" and the necessary components to build a larger reactor. I prefer a reactor because its air tight and doesnt allow the solution to come in contact with O2.

[alexwolf]

Depending on the plumbing, I can get you a 8" acrylic tube if you want Steve. Maybe we can make something that way?

[GaryP]

Would it be better to do a couple of mix/settles cycles per day. I'm wondering if you are flushing the dissolved Kalk and then nothing but RO water going through the reactor after that unit the next day.

Gary

[alexwolf]

Doesnt kalk have to settle for quite a while before you dose it? That would eliminate stirring it several times a day.

[GaryP]

Huh?

[alexwolf]

I was under the impression that the kalk needed to settle for a while before you dripped it. If that is the case, you cant stir it several times a day, you let it settle during the day, then drip at night. After you drip, it stirs it up again.

[RobertG]

Just think how little the saturated water would do to a volume of 600+ Gallons. Nothing. I would stir it up every other hour or two. Then let it dose in the sump. Then again I might be just thinking that would work.

Jim you gonna call me?

[GaryP]

What I was referring to several stir, settle, pump cycles per day. That would have the effect of putting more Kalk into solution per day. Its not doing any good to simply pump a large volume of RO water through the unit if you are only stirring once a day. You may not get the entire RO volume that you need for makeup, but there are other ways to add that besides going through the reactor.

Its obvious the current method isn't meeting his calcium and acid neutralization demand. The only way to increase the input is to go to a larger chamber, as was mentioned, or to increase the amount of material being stirred with the present chamber. The only way to do that in a certain period of time is to increase the stir cycles per day.

Gary

[NaCl_H2O]

It takes about 2 hours for it to settle out well. Some do just drip the slurry (unsettled) but from what I read that is just adding solids that aren't helping.

JimD, in effect, I am building a larger capacity reactor by recirculating the Kalk water back into the resovoir ... I hope! I'm probably going to give this configuration a try this weekend and see how it works for the next week or so?

[NaCl_H2O]

Gary, I agree completely. I intend to try a mix/settle/recirculate cycle several times overnight to get the resovoir saturation up enough for the next day's supply. Currently, I think the amount held in the reactor is quickly dilluted and I am dosing mostly highly dilluted Lime during the day.

The main point of the post was: Did everyone feel that dosing .25 - 1.0 gallons of limewater within a matter of 10-20 seconds was safe for a 400-500g capacity system?

[GaryP]

My understanding is that adding the unsettled slurry is very dangerous. It will kill anything it comes into contact with.

Gary

[RobertG]

If there is alot of flow in there it is going to disapate fairly quick before hitting the tank I would think. I have dosed it like this with no issues. I have lots of flow going. What kalk are you using? I am dripping it so it does settle, just for the most part it is going in pretty fast. As the Top off would do. I also use a Calcium dispensor by Tunze.

Maybe have it does after the stir 10-15 minutes or so. Just to be safe.

[NaCl_H2O]

Robert, the flow in this area of the sump is VERY brisk, and passes through a pile of LR rubble before getting to the return pump.

Here is another question: How can I determine if my resovoir of limewater has reached saturation? From the article referenced above, a PH of 12.54 (@ 25 DegC) sould mean it is saturated. Also, conductivity of 10.3 mS/cm also indicates saturation. My salinity monitor (PinPoint) displays Salinity in mS - is this the same as conductivity? (i.e. Salinity of 49.5 mS = 1.024 SG), can I use this to look for a 10.3 mS/cm conductivity of the limewater??

Thx - Steve

Uh oh ... this is a chemistry question & Gary is reading this post :o Brace yourself :shock:

[RobertG]

I could'nt tell you. I think just seeing it all stired up is enough for me. You have lots of water I dont think it will get outta wack from some Kalkwasser. I would think you could use the salinity monitor. How do you like it? I have one & it jumps around alot.

I guess I will try to recalobrate it. Just seems like the pinpionts jump around alot. I have the PH monitor too. The temp probes would never sink up for me.

I dose into my sump just before the return pump inputs. It is very brisk as you say. I always watch the returns to see if I see any cloudiness. Never.

You'll figure out what works for you.

[NaCl_H2O]

I would think you could use the salinity monitor. How do you like it? I have one & it jumps around alot.

I guess I will try to recalobrate it. Just seems like the pinpionts jump around alot. I have the PH monitor too. The temp probes would never sink up for me.

I have the Pinpoint PH, Salinity, and Temp/wireless monitors - thay all work great - and steady! However, I am runing them all off batteries. If I connect the Salinity monitor to the AC adapter, it jumps all over the place, even after adding a ground probe? For now, I just feed it a fresh rechargable 9V battery about once a week :cry:

[GaryP]

Steve,

Believe it or not, I'm going to pass on this one. I've never used an analytical approach to dosing Kalk. Of course I don't have all the toys you have. I just open a valve and let it drip. I would suggest that you try to make your Kalk water reservoir as air tight as possible to prevent precipitating CaCO3. Even if you do precipitate some, it should be a fairly small percentage of the total.

As for doising that fast, I guess the main question is going to be the biological impact immediately downstream of your addition point. You said there is a lot of rubble to provide mixing, but you are still going to have localized "hot spots" of high pH that will occur almost instanteously after addition starts. I'm afraid that your rubble may turn into a dead zone whose only purpose is to serve as a static mixer. That may be OK in the overall scheme of things in a system your size. I can't really visualize where you are adding the Kalk.

Remember you may be raising your pH a few tenths in the bulk water, but would be raising the pH in the mixing zone by a unit or two. Changes in pH are not arithmetic. In other words, dilution is not the only factor. These large swings in pH may not be tolerable for any critters living there. I guess I would rather see a much slower addition rate. Even raising the pH a few tenths in a short period of time in the bulk water may not be a very good idea. This is one reason we have moved progressively to longer acclimation times when introducing new critters. Obviously, differences in salinity are a major concern in regard to acclimation, but to a lesser extent so is pH and alkalinity. I would rather see a slow, almost constant addition. I believe that is what Jim Norris recommended based on his experience with his 240 gal. system.

Gary

[JimD]

Your meters are freaking out because of the rfi being generated by your lights, common, stick with the batteries. A kalk solution that has reached saturation will be in the 12.4 Ph range. I use a Ph monitor so Im constantly aware of its level, I dont measure the Ph of the solution, rather the Ph of the tank, when the Ph begins to fall, I know its time to recharge the reactor. Personaly? No way would I use the slurry method, I know some people out there use it successfully, but to me, it seems like an accident waiting to happen.

[GaryP]

The expert has spoken. The other thing is whether you are calibrating your pH meter with a pH 10 buffer so that it is accurate in that range. Most people I know only use a pH 7 buffer. In a lab we usually used at least 2 pH standards, and occasionally 3, to get a good calibration.

Gary

[NaCl_H2O]

Gary, JIm, and everyone - thanks for the input, all good advice! I think I can adjust my topoff system so that I get smaller amounts of dosing, more frequently.

Jim, I am also monitoring PH of the tank constantly. That's why I know that I am not keeping up with the dosing needs.

Gary, precipitating CaCO3 is one of my concerns, guess I'll need to se how it goes, and adjust as needed? I do calibrate ever month or two with PH 7 & 10 cal standards.

Thanks!

[GaryP]

How far off is your calibration when you do it?

Gary

[NaCl_H2O]

I started working on my increased volume Kalk Reactor last night and it occured to me that I was making this way too difficult, and decided to take the KISS approach!

1) Re-installed the MAG2 top off pump in my RO/DI resovoir, with top off controller turned off at night
2) Installed a MaxiJet 1200 in the resovoir, mixes 15m every 2 hours while top off controller is off
3) Dump Calcium Hydroxide straight into the resovoir

Done ... I think Pete had a post awhile back about keeping things simple :grin:

[Tim Marvin]

I do it just like this in one of my tanks and have noticed no problems. I am not so sure that the air contact makes much difference, (against popular belief). Also the tunze on the other tank doses all the kalk in the reactor within a week it is just clear water in there, nothing on the bottom. I have great coralline growth in both of these tanks.

[NaCl_H2O]

How far off is your calibration when you do it?

Don't have a clue? I'll pay more attention next time and let you know :oops:

[GaryP]

Steve,

How far out of calibration your meter is would be an indicator of whether you need to calibrate more often or not. "A craftsmen is only as reliable as his tools." In the lab, we calibrated on a daily basis and soaked the electrode in KCL between uses. That's probably not necessary in your case because sea water contains a lot of potassium that can be used to regenerate itself.

Gary