High PH after dosing kalk

[Horace]

Well as I expected my PH is a bit high now after a week of dosing kalk. I eventually decided on a kalk reactor style of feeding my tank and dripping about 1 drop/sec. However, this still doesnt seem to keep up with my evap. Anyway my PH is now at about 8.5 - 8.6. I would like to keep it closer to 8.2 if possible. Im not sure if this is a temporary thing or not while my tank is no longer getting any doses of Reef Builder. At this point I am not even going to try to add more to match the evap because Im thinking that may just raise it even higher. One thing I did last night was to make it so im only mixing 2 times per day at 15mins at a time. I was stirring 8 times a day for 15 mins and I think it was making the kalk too concentrated and dripping too much unsettled kalk. Your thoughts?

[Horace]

Also I wanted to note that I have increased the speed of the fan over my sump hoping to increase the CO2 exchange. Also I really would rather not have to deal with adding vineger or soda water to my tank all the time...That is just as bad or worse than it would be to just add two part all the time, and in that case I would just stop using kalk all togeather.

[Randy Holmes-Farley]

You can easily back off on the tank pH by stirring the reactor less often, but that will decrease the amount of calcium and alkalinity added. I'd stop the fan, as it is mostly just increasing evaporation.

More aeration of the water (not a fan, but a skimmer or an airstone) will bring down the pH.

What is the alkalinity now?

This article has more info:

High pH: Causes and Cures
http://reefkeeping.com/issues/2005-03/rhf/index.htm

[Horace]

Yeah I read that article....I do have a sizeable skimmer but perhaps I could try an airstone as well?? The alk is running ~8.5 dkh. It was about 9dkh before I started the kalk drip. Ive only tested it once since starting the kalk because i wanted to see what it would drop to or see if it would hold it at or above 8dkh with the amount im dripping now. I dont like letting my Alk get below 8dkh so I guess we will see what happens. Before I started dosing kalk my tank is eating about 4dkh a week which was a pita to keep up with dosing reef builder.

[Randy Holmes-Farley]

Try aerating a cup of water with an airstone when the pH is high and see if it drops.

[Horace]

Oh btw, if it takes backing off on the kalk stirring to bring down the tank PH im fine with that. It will still make it much easier to maintain the tank alk/calc I think.

As a side note: to use your two part, do you indicate anywhere how much of each part to add to stay in balance? For example I typically add about 1dkh worth of alk at a time...how much calcium does that correspond to adding? Up until now it has just been a guessing game for me and trying to keep the alk at ~8-9dkh and the calcium 400+ ppm. iVe used the calculator to figure out how much to add to raise the levels a given amount, but I am not sure if that is necessarly in balance...

[Randy Holmes-Farley]

Oh btw, if it takes backing off on the kalk stirring to bring down the tank PH im fine with that. It will still make it much easier to maintain the tank alk/calc I think.

Maybe, but you are also dosing less.

As a side note: to use your two part, do you indicate anywhere how much of each part to add to stay in balance? For example I typically add about 1dkh worth of alk at a time...how much calcium does that correspond to adding? Up until now it has just been a guessing game for me and trying to keep the alk at ~8-9dkh and the calcium 400+ ppm.

I'm not sure that I understand, but always dose equal parts unless there is a significant problem. This calculator shows how much to dose to raise alkalinity (or calcium) by a specific amount (like 1 dKH):

Reef chemicals calculator
http://home.comcast.net/~jdieck1/chem_calc3.html

[Horace]

Originally posted by Randy Holmes-Farley
Try aerating a cup of water with an airstone when the pH is high and see if it drops.

You would think the drain alone would aerate the water plenty. That puts tons of bubbles into the first chamber of my sump. Then I have the skimmer as well. I totally trust you that aerating could help, but man I think I would have to pump quite a bit of air into the water to make a difference over what I am already doing. Would creating a bit of a waterfall in my last chamber help as well? I typically keep the topoff set to where there is almost no fall over at all from the second chamber to the final chamber where the return pump is located. Either way I guess I could borrow somones airstone and see if that helps....

[Horace]

Ok I think I have the calculator figured out...It says if I want to keep Alk at 9dkh that balanced calcium is 425ppm. So I need to find out how much alk/calc I lose over time to guage exactly how to maintain it at both those levels. I track the alk loss quite a bit more closely than the calc loss. Typically I dont like letting the alk drop more than 1-2 DKH before adding more reefbuilder. Is there somewhere to determine exactly how much calcium corresponds to a 1 dkh increase? I hope this makes more sense.

[Randy Holmes-Farley]

Complete equilibration of CO2 is far harder than most people think. With complete aeration, your pH would be pegged at about 8.2-8.3 with no daily swing at all. I'm not saying it is easy to accomplish, only that it would work.

[Horace]

OH one more thing :P. Your calculator says that to raise the tank (75g) 1dkh, it takes .65g of limewater. I am probably dosing on the order of 1g+ per day because thats what my evap is. That means that I am adding almost 11dkh per week (7g/.65g = 10.7). Perhaps I should just cut back?? I know I dont use that much Alk per week for sure right now.

[Horace]

Originally posted by Randy Holmes-Farley
Complete equilibration of CO2 is far harder than most people think. With complete aeration, your pH would be pegged at about 8.2-8.3 with no daily swing at all. I'm not saying it is easy to accomplish, only that it would work.

Well I guess its worth a shot anyway. Just curuios but how long should I aerate the cup of high PH water to see if it makes a difference? I would hope it would bring the ph down quite quickly given such a small amount of water. So does high PH automatically mean that my CO2 levels are low? I know adding Co2 will lower the PH, but I dont want to have to add an excess (above normal levels) of CO2 just to keep my PH at the norm.

[Randy Holmes-Farley]

FWIW, it isn't my calculator, I just use it. RC member jdieck wrote it.

It is hard to make such determinations by calculator. Trial and error is the best way to determine the demand, which varies with pH and alkalinity level. Your reactor may also not be delivering saturated limewater. many do not.

[Horace]

FWIW it isnt exactly a "reactor" its really a large tub (10g or so) that i have a good amount of pickling lime on the bottom. I have the tub elevated above the tank. The outlet is about 8" off the bottom of the tub and the tub auto fills via an RO/DI float valve. I have a very small rio pump that used to mix 8 times a day for 15mins at a time. Now I have it set to mix twice a day for 15 mins because I think I was getting super satuarated limewater (it looked VERY cloudy)

[Randy Holmes-Farley]

OK, in that case you may well have dosed more than comes in saturated limewater.

[Horace]

Thats what I am thinking as well...Im hoping that by dropping the stirring schedule it will give me the results Im looking for and still keep my alk/calc up. As I said if I dose 1g/day of saturated limewater thats much more alk than I use per day (about .5dkh more) anyway. So if the water isnt fully saturated with the new stirr schedule I think I may still be ok.

[Randy Holmes-Farley]

Sounds good.

Good luck and let us know what happens!

[Horace]

Well it seems my PH has come down a tad after reducing the stirring frequency, its back in the range of 8.4 - 8.5 where before I would say it was closer to 8.6. However it remains to be seen if the calc/alk is being maintained properly. My tank used to run at about 8.4 - 8.5 even before I started dosing limewater. Im not sure if that is because of the reefbuilder or what (any ideas Randy?). It seems strange why it would be that high otherwise. Given that I use an overflow which puts a substantial amount of air into my sump, and also a fairly large skimmer for a 75g.

BTW I see what you mean about CO2 and PH. Just for the heck of it I tested my PH this morning and after I got a good reading I breathed into the test tube a few times. It QUICKLY brought the PH down to like 7.7 from 8.5ish (Turned from dark green to yellow)

[sjm817]

Why do you mix so long? It doesn't take very long to stir Kalk up. I've tried a bunch of different setups. My current thinking is stir often, stir gently. I use a digital timer, and a magnetic stir bar. The minimum the timer can run is 1 min. I do this every 2 hr. Even with the stirrer turned to a very low speed, it is enough to raise a cloud of Kalk just to the top of the chamber, which is more than saturated.

You want to add clear saturated Kalk, not the solids. With a stir often, stir gently setup, I think I have a setup that always has good saturation, without having it stirred so much that I'm pumping in solids.

The Deltec Kalk reactor stirs nonstop @ like 1 RPM. I'm trying to emulate that idea without spending the $$ on one.

Another thing you can try is to stir more at night, less during the day when PH is higher.

Kalk wont keep up with the demands of my tank. I still have to use a daily 2 part.

[Randy Holmes-Farley]

My tank used to run at about 8.4 - 8.5 even before I started dosing limewater.

Never lower in the AM?

[ReefMalamute]

Randy I really didnt track it enough to find out. I always viewed PH as something that I dont have a lot of control over. I had to add the things I added (calcium/alk) and other than that I wasnt worrying about it. That is until I decided to dose kalk, now I pay much closer attention to it.

As for my mixing time, my timer has a min of 15 mins I think (whatever the min is on a typical lamp timer anyway). I dont have a electronic one.. though I understand it would be better if I did. Thats just one more than I should purchase down the road.

[Randy Holmes-Farley]

Try measuring pH in the morning to see whether it is high then too,or just high the afternoon. There would be different ways of dealing with the two situations.