Help!! Low pH

I know this is generic, but what am I doing wrong with my pH? My pH has dipped to 7.57. I was holding strong at 8.1 and then it just started going down over a few weeks...

I have lime soda in a reactor going into my skimmer to try to remove co2. And i add kalk to ATO. I can't think of anything else that has changed...

What is going on?

 

81 degrees and humidity right now prevent that as an option unfortunately... so it has been a few days since the windows have been opened. Gotta love Iowa weather!

 

So what do people do in the winter? 30 degree iowa weather and windows open obviously isn't realistic. Is there no real way to keep pH up without windows open?

 

So about the comment "don't chase pH". I have heard this mentioned several times in reference to "chasing numbers" in general. And while I understand the concept of "if it ain't broke, don't fix it", I am not sure I completely understand it here. Don't the corals require a pH of between 8.1 and 8.3 to maximize their growth? And with my pH down below 7.6, isn't it safe to say that this is not a "healthy tank"? I do get the whole "don't nit pick" over numbers, but to me it seems like those numbers are there to tell you what you should aim for, and if something is quite a ways off, do what needs to be done to correct it, yes?

As far as "what has changed" - I have increased the lighting in the tank. Would this have any kind of bearing on the pH levels? And when I say increased, I don't mean duration per day - just the intensity of the lighting. Also, I have started to have a bit of a cyano breakout as of late. Perhaps the presence of this bacteria is lowering the pH? Just trying to think of anything that has changed.

I do have a refugium going, and I keep the lights on opposite my display lights (or at least with little overlap). The only plants that I have in the refugium are chaeto algae.

My probe is a fairly new pH probe from Atlas Scientific. I have not as of yet tried to recalibrate it. I suppose that is possible, but seems unlikely as it is only supposed to be recalibrated once per year and it has only been used for a few months.

We try to open the windows when we can. What other suggestions do people have? DO I perhaps need a kalk reactor? Thinking perhaps that the solution is becoming unstable of settles too much before it gets mixed into my tank?

 

I have checked the probe - doesn't appear to be an issue there...

I had some old carbon media that hadn't been changed forever - that couldn't have been helping. So I bought a BRS dual GFE reactor and installed that with carbon and GFE. I also changed out the media in my CO2 scrubber (it shouldn't have been old but you never know). Those two things combined seemed to have helped. I am up to 7.78. Still not great, but better than 7.51.

I did built myself a kalk reactor too. I am going to be using that in conjunction with my ATO. Previously I was just dumping kalk powder into my ATO, but I don't think that was really helping much as it would all settle and over time just go bad. So this should make a difference too. I am hoping to have it up and running tonight. I have it built - I just need to modify some C++ code in my controller to get it working.

As far as the cyano causing me grief, I wouldn't be surprised if that is contributing to the problem, but am not sure what else to do to get rid of it. I am hoping that the GFO reactor may help with this as my understanding is that it can reduce phosphates which help spread the cyano (although if I am wrong on this assumption let me know!) I ordered a phosphate tester and am hoping it shows up today...

 

I would always welcome a second set of eyes and second validation that my probe is working right.

I am pretty new to the world of reef keeping, so it wouldn't surprise me if I am making a rookie mistake!

Another thing that I find a little odd is that my salinity keeps dropping. When I do a water change it is usually around 35ppt, and in the last 10 days it has dropped to about 32.5ppt. Not a huge deal, but I just find it off. Yes my protein skimmer does pull a bit of water out and is replaced by RODI water from my ATO, but I wouldn't think that it would cause that much of a difference. My sump does get a little salt splash build up, but I still wouldn't think that much? It is a pretty small tank (65 gallon + 29 galloon sump) but that is still more of a dip than I would expect... I would guess my skimmer has pulled out maybe 2 gallons of water in 10 days?