Calcium Dispensor Set-Up

[demariners]

So I currently run a calcium reactor on my system to maintain the alkalinity and calcium. That seems to do a great job but my pH seems to drop to about 7.7 and I can not increase it. I purchased a calcium Dispensor thinking it would help with this issue but so far after three days it still remains at 7.7-7.8 and rarely moves. I am puttin 2-4 teaspoons in the unit. Should I be putting more in there? My tank is 67 gallons and I usually displace about 1.5 gallons per day. I do not really care to use this for calcium and alkalimity management but to increase my pH. Any other suggestions would be greatly appreciated.

 

[rvitko]

I would add 2 tablespoons (6 teaspoons) and it takes time. It might also be wise to do a good size water change just to account for any beginning imbalance of ions (low magnesium or high bicarbonates for example). Kalk works to slowly raise pH by raising alkalinity and it does this two ways, the free -OH and by binding to free CO2 to form carbonates. In general it takes at least a month of steady dosing to see a real difference in pH stability.

 

[demariners]

When you say pH stability.....do you mean a rise as well as stability? Currently it is low and I am hoping the unit will also raise my pH. You said low magnesium but I just checked it and it is perfect at 1350 ppm. Also you said high bicarbonates? Not sure what you mean but my calcium reactor keeps a steady 9.5ish ALK and 425 ppm calcium.

Again this just started happening with the addition of my reactor. Will the effect of MORE kalk in the unit effect my reactors ability to stabilize the alk/ca in the tank? I will also do a water change. I did one last week at about 15% and I try to do them every 2 weeks. I had a steady 8.1-8.2 ph when I was using 2-part dosing but it was never enough to keep up and that is why I got the reactor. After about a week of having the reactor i noticed it slowly decreasing and eventually evening out around 7.75-7.8. Thanks again.

 

[rvitko]

Yes, pH is determined largely by the ratio of CO2, -HCO3 and --CO3, likely you have a lot of free CO2 and a fair amount of -HCO3, this will result in a lower pH than a higher level of --CO3, over a month or so, the kalk will bind the CO2 and HCO3 and raise the pH. You might also consider backing off the CO2 a little or slowing the drip rate of your reactor, just a small change, this will reduce the free CO2. More flow and surface agitation will also help.

 

[demariners]

Well I put in 3 TBSP just in case. I have my flow at 40 ml/min. Not sure I want to go less but I essentially could. I have only had the dispenser up for 2 days. I will give it a couple weeks and see if I get any results on the pH. I have a lot of aeration (skimmer, drain into a sock, and ecotech marine powerhead). I hope that is enough. Also I have fresh air coming into the sump and over the top of the tank from the outside. I have tried everthing so I purchased your unit so i am hoping this does the trick over the next few weeks. I am just hoping that my alk/ca don't get out of wack with my reactor working the way it does with the balanced addition. I may have to do some more tweaking of the reactor to compensate for the kalk addition?

 

[rvitko]

Yes, it is a balancing act and the only way to simplify it is if the reactor is pH Controlled so it only turns on when the tank pH is above 8, over time you can work that up to 8.1 (with a better controller 8.15). Then when the dispenser comes on, pH goes up, and the reactor turns on. Even then achieving stability takes 2-3 months but is much improved after 4 weeks. pH in seawater is almost entirely based on the carbonate equilibrium and with a high CO2, you have to drive out or reduce some CO2 and raise the carbonate hardness to get to the level you want. It isn't going to be an instant process, especially if you are doing it manually and also need to manage drip rate and bubble count. Eventually when you get the equilibrium right, the pH should stay steady between 8.0-8.2.

 

[demariners]

Well, I wish I could do that. I have the reactor on 24/7 with a pH probe that monitors the reactor's internal pH. I keep that stable and have the CO2 turn off and on with the pH to keep it stable. If I was to have the reactor pump off below 8.0 then the reactor could possibly not be on for a period of time and therefore my Alk/Ca would fall. My tank has a very high demand so daily I lose about 3 dkh/20-30 ca.

 

[demariners]

I am thinking I will keep everything as is for now and then see if my pH rises in the next couple weeks. After about 4 weeks if it is still the same I will try something different. Is it wise to add MORE Kalk if that is the situation? At this point I will need ot balance my alk/ca with the kalk addition as well.