Dosing kalk based on ph?

[dascharisma]

I currently add limewater to my tank 3 times daily in order to keep my calcium and alkalinity in check, as well as to raise my ph which was always low before I began adding kalk. I would like a way to automate my kalk additions, but for a number of reasons I would prefer to not use an auto topoff system. Would it be ok for me to set up a dosing pump that was controlled based on the ph of my tank? I would have my aquacontroller turn on the pump when the ph fell below a certain value and turn off when the ph reached a proper level.

Does this sound like a workable plan? My current values are calcium 420, alk 9.9 and my ph fluctuates between 7.95 and 8.1. I imagine that kalk would mainly be added at night with this dosing setup. Do you see any problems that I should be aware of? Will my calcium and alk be ok if the limewater additions are based on ph?

Thanks in advance
Brad

[steve the plumb]

I got the Tunze osmolater with the cal disspencer.This is a perfect unit for someone like you.It fills up evaporated water with kalk water and maintains ph and alk.My ALK is a steady 9.6 dkh.My PH is 8,it always used to be at 7.88 7.9 My calcium is at 450.The unit works with evaporation so it goes on every so often.It comes with an electronic eye that sets water level and a float alarm just incase the eye gets dirty and malfuction the float switch stops the unit.Do you add Randys 2 part formula?If so maybe you want a doser pump that does kalk plus another 2 elements.Then maybe you would want to buy the Sentry doser or Spectra pure litermeter.If you find that kalk water does the trick I think you will be happy with the tunze.

[dascharisma]

Thanks for the reply.

I have considered an auto topoff unit, but I have decided that I would like to avoid using one. I have two reasons for this. My first problem is that I run a bare bottom tank and I have to siphon on a regular basis. Everytime I siphon I take out 5 gallons of water. That means that I would have to replace 5 gallons of salt water every day to avoid letting an auto topoff lower my salinity. My second problem is that I skim very wet and my skimmer production fluctuates wildly. Some days i skim around a gallon of water and other days I produce more than 5 gallons. That means that if I ran an auto topoff I would need to constantly monitor my skimmate production in order to add the appropriate ammount of sw back to the tank. I would rather deal with a small daily addition of freshwater to account for evaporation minus kalk addition, than have to deal with the aforementioned problems.

Brad

[Randy Holmes-Farley]

If you set up a dosing pump, what pH would you control it at? How do you know if a particular pH will satisify calcium and alkalinity?

Why "control" it by pH at all, and not just dose a set amount?

[dascharisma]

The reason I thought it might be a good idea to control the dosing of kalk based on ph is that I am having trouble keeping my ph stable. I figured that I could try dosing at different ph levels until I found one that would keep up my calcium and alkalinity. I would be happy with a ph anywhere between 8 and 8.3. I guess I could be wrong, but I didn't think it was too important to dose exactly the right amount of kalk. In other words, if slightly too much kalk is added, then alkalinity should raise which would increase demand via calcification, and vice versa. I know that many people dose limewater to replace water lost to evaporation, but this seems fairly arbitrary to me. My tank evaporates way more water than most tanks with my calcium demand.

Do you think I should scrap the plan to control the dosing of kalk based on the ph? Should I just dose a specific amount each day? If I don't use ph to control the dosing, how should I keep my ph stable?

Thanks in advance
Brad

[examiner]

I'd be against the idea, just way too many variables I think. I view kalk as a "bonus" I get to add w/ my top off water.....but the primary purpose (for me) of the whole process is to stabilize salinity. The PH raise is a nice bonus, that's why i limit my dosing to lights-off periods.

What kind of a PH swing are you experiencing now? I believe everybody has a swing of some sort, and as long as you stay within "established" parameters I wouldn't worry too much about it. I'd assume, like most, that your PH is lowest during the night, so I'd recommend just dosing a set amount each night based upon your evap rate. I can basically keep my swing at .1-.2 by this method, and that doesn't worry me at all.

[examiner]

Might also add that i use a peristatic pump on a timer for my kalk topoff. With a little trial and error, I was able to figure the pump speed/hours needed to match my evaporation. If you do something like that, you wouldn't be at the mercy of a float switch which might push down your SG.

[Randy Holmes-Farley]

I do not think it necessary or desirable to control it by pH. If you want to raise the nightly low pH, put the pump on a timer. :)

[ReefWaters]

Randy,

I run a float switch in my sump to control evaporation. I add fresh water via a pump in a bucket. I also use a calcium reactor to stabilize my CA and Alk.

If I continued using the above methods, and added a kalk reactor which dosed limewater when the pH was below 8.0 (mostly at night), would this still be undesirable? Would it cause my CA and Alk to swing or would the whole system stabilize itself eventually? Is it bad to swing into the 7.8 and 7.9 range at night?

Thanks for all the help,

ReefWaters

[Whaledriver]

This sounds like an interesting idea. The biggest problem I have had is keeping my ph up and stable. My salinity, CA ams ALK dont go to far out of range in a week. I cant say the same thing for my ph.

I would love a system where I could set up a bucket of kalk that wouldnt be too much to throw off salinity too much if it were all dosed. This could just be pumped whenever the ph goes below a set point.

If I do this as well as top off with kalk and use Randys 2 part system It would solve most of my upkeep issues
I wonder what percentage of tanks crash because ph goes out of control? My guess is that its a leading cause of crashes.

[Randy Holmes-Farley]

it is not optimal to swing down to pH 7.8 or 7.9. If the pH is that low, I'm not sure you need any pH control on the limewater addition. A timed addition is OK, or just straight 24/7 dosing.
I wonder what percentage of tanks crash because ph goes out of control? My guess is that its a leading cause of crashes.

In all the limewater overdoses that I've ever heard of (dozens),only one lead to a real crash, and that was a huge overdose with the pH well over 9 for a long time.

[Whaledriver]

I was thinking of the ph going too low and leading to a crash. This would one reason to keep the ph above 8 at all times. At what point is low ph too low? Since I have a digital ph meter I can see the swings during a 24 hour period. Without it I would just assume things are ok and not see that it can get down to 7.7 in the morning.

As always thanks for the help to all of us Randy.

[ReefWaters]

<a href=showthread.php?s=&postid=6515726#post6515726 target=_blank>Originally posted</a> by Whaledriver As always thanks for the help to all of us Randy.

Yes, I agree, THANK YOU VERY MUCH Randy!

I may add the kalk to the system here in the near future. Its been doing fine with the low swings at night but I believe it could do better. But I want to watch my daily PH swing for a week or two.

I actually just switched from a Milwaukee PH controller to an AquaController Jr so now I can look back over a few nights and see what the PH is really doing. But the AC Jr reads to the second decimal place where the Milwaukee only read to the first. I think I need to calibrate the probe. Its been a year and I haven't calibrated since setting up the Jr.

Can I get 7.0 or 7.1 calibration fluid somewhere locally without ordering it? Where would I go?

Thanks to everyone for the help.

[ReefWaters]

Oh and one more question for Randy.

Is it okay to add magnesium and strontium supplements to a kalk reactor (specifically Seachem Reef Advantage Magnesium and Seachem Reef Advantage Strontium) or would that cause some problems with the kalk? Would it be better to add those to the top off water?

[Randy Holmes-Farley]

I would buy pH 7 and 10 calibration fluids at an LFS or online. There are no good home substitutes, although you can confirm proper operation (or not) using borax:

Borax pH Calibration
http://web.archive.org/web/20001102182839/http://www.animalnetwork.com/fish2/aqfm/2000/feb/bio/default.asp

No,you cannot add magnesium to limewater. It will precipitate as magnesium hydroxide. Strontium is OK, although I do not think most people need to dos eit.

This article has more:

Magnesium and Strontium in Limewater
http://www.advancedaquarist.com/issues/dec2003/chem.htm

[ReefWaters]

Randy, thank you again. :thumbsup:

I think Ive got all the info I need to make some decisions.

One last question.

Can the Magnesium and Strontium supplements go in the top off water together without reacting?

[Randy Holmes-Farley]

That depends on exactly what they are, but most could be combined, yes. :)

[steve the plumb]

when I do my water changes I just unplug my auto top off unit so thats not a big problem if you do water changes often.You can close the unit when you want to.I also purchased a dosing unit you might want to try that you could dose kalk water by timer as well as alk and calcium.I am using the aqua medic and find once you get the right dosage its very simple to maintain.