Kalk Reactor for pH control

[tmz]

OK. As long as you bring that up, there must be swings in Alkalinity on an ocean reef as well. How much and over what time frame?

"The alkalinity of natural seawater is primarily a measure of bicarbonate plus two times the carbonate concentration. In the ocean, it varies by location and depth. In surface waters, it usually varies between about 2.25 and 2.45 meq/L (6.3 to 6.9 dKH), and often varies with changes in salinity. In deep water and upwelling water, it may be higher due to dissolution of calcium carbonate that is driven by pressure. thats from Randy's article entitled What is Seawater?."

The alkalinity( more specifically the amount of carbonate/bicabonate available) varies in response to variable conditions including specific gravity , I'm not aware of nor could I find a study indicating shifts within a 24 hour period at a specific reef location unrelated to run off or other sg altering events. I'm not clear on when coals actually do most of their calcification day vs night either.

 

[rogergolf66]

Ok so I have read randys article on what your grandmother never told u amount limewater I think was the title. I have been dosing Randy's 2 part. I noticed that my ph is very low 7.7-7.9 end of light cycle. My tank is sps dom. I have noticed when the alk gets over 9dkh by mistake a couple of times tring to dial in the dosing amounts as corals grow and I have added more corals I get much better growth. So I started doing some more reading and learned that on tanks with low ph that a higher all and cal seems to help increase growth. It also said if ph is high 8.5 then hight Ali and cal does not help increase growth. Don't push all parameters it says.

Well to my question. I would like to see my ph near 8 so I added a kalkwasser reactor. Here is my question how do u know when the kalkwasser have been used up and u need to add more kalkwasser into the reactor?

 

[bertoni]

The solids at the bottom of the reactor should decrease a lot in volume. There's no other good sign. You could try testing the conductivity of the output water, but that requires a meter with a suitable range.

 

[redtop03]

Many folks dose their limewater only at night, but I choose to replace evaporated water with limewater 24/7. Putting it on a timer might work, but it is one more thing among many that might fail when I'm away on vacation.

I only dose kalk at night time from a stirrer to help stabilize the pH swing...I have the feed pump connected to my AC Jr. controller,as soon as I can figure out how to use the pH probe to monitor and control it,I'll use that route...

I've had too many simple timers to fail so I don't trust them for anything of importance on my tank

I like that kalk is the most economical means to replenish Calc/Alk ,but I also dose 2-part because with only dosing kalk part time,it doesn't keep up with the demand

 

[tmz]

When I think about diurnal variations in the tank, I fret about night time hypoxia more than ph swing.
I prefer 24/7 limewater dosing for the reasons noted in my earlier posts to this thread( constancy isn alk, calcium and sg ).
Eric Borneman did series of articles called The Rght to Breathe, IIRC. When photosynthesis stops there is less O2 in the water; localized hypoxic conditions that last for very long can cause harm to corals .

Running tanks or refugia containing macro algae or other photosynthetic organisms on opposite photperiod can offset the O2 drop as may gas exchange enhancements. For example , if you run more than one tank with photsynthetic orgainsms and it's integrated to the other(s) photoperiods can be staggered. These techniques also helps steady the ph.

The night time O2 drop in out tanks is more of a worry than diurnal swings in ph ,imo. It is often overlooked in the rush to focus on keeping ph steady across the 24 clock which is not a really big deal as long as the low is 7.8 or higher and the high 8.5 or lower,imo.

Just something else to thin about along with ph control.

 

[cfsindorf]

Randy: If I am going to set up a settled reservoir how do you know how much calk to add to it? I have a 60 gallon cube that I dose and would lrather just do one instead of 2 so I thought of going to calk in a reservoir. Do I just dump a bunch in the bottom, fill it with RODI and let the ATO do its thing?

 

[t.trezona]

The simple answer is the pH will begin falling as the Kalk is exhausted. When that happens it time to recharge. In my reactor that would happen at about 2 months. Also, my reactor vessel was clear so I could watch the solids dissappear over time. However, there will always be solids left even when there is no more CaOH left in solution. If you have a controller that you can monitor in terms of frequency of Kalk delivery to your system, it will go up (the frequency of delivery) as the Kalk becomes exhausted and the solution from the reactor no longer is able to raise the pH. A problem with this is more and more fresh water will be added to the system so your SG goes down if this is greater that evaporative losses so you have to pay attention.

 

[tmz]

For a settled reservoir you can add the kalk two tsps per gallon plus a little extra when you fill/refill it. You can use less if you like. Any extra will settle to the bottom as undissolved kalk. It can be restired in when you refill.

 

[redtop03]

The simple answer is the pH will begin falling as the Kalk is exhausted. When that happens it time to recharge. In my reactor that would happen at about 2 months. Also, my reactor vessel was clear so I could watch the solids dissappear over time. However, there will always be solids left even when there is no more CaOH left in solution. If you have a controller that you can monitor in terms of frequency of Kalk delivery to your system, it will go up (the frequency of delivery) as the Kalk becomes exhausted and the solution from the reactor no longer is able to raise the pH. A problem with this is more and more fresh water will be added to the system so your SG goes down if this is greater that evaporative losses so you have to pay attention.

ah,never thought of that,thank you