Alright, I needed to do some testing overnight before I could come to a conclusion. Well it is now the next day, and what I thought was happening is actually happening. And I have absolutely no scientific idea why at this time.
As I'm sure most of you know, this week (last week I guess) on Monday was Labor Day in the USA so I 'kind of' had the day off... Basically because of the holiday, I had to leave out for work on Monday rather than Sunday. Well on Tuesday I was sick as a dog and came home and have been here ever since trying to get over this cough. It's horrible. Well on Monday after I left, the ATO in the tank went low and the wife put fresh water in it. I know, I should have done it myself. Well since then my PH went from 8.25 to 8.35 all the way down to 8.0. A very high swing that hasn't happened since I recalibrated that PH probe. I asked her if she put Kalk (Pickling Lime) in the water to raise the Calcium and Alkalinity and she said she did.
When I got home Tuesday night, I didn't care and didn't even look at the PH or the tank for that matter, I just wanted sleep and copious amounts of medicine to get over this crap. The next day I noticed the PH was still very low and again I asked her and again she said yes. This went on until Friday lmao. She is pretty pissed at me over this one lol.
So this weekend I decided to do a little experiment. My refugium flows very slow and has accumulated a lot of detritus. I first was thinking this could be the cause of my algae in the display tank but I figured when I do the second water change in two days (more on this later) that I would clean out the fuge and fill it with fresh water. Well, before I did that, I just went ahead and shut off the flow to the fuge and started getting some new fittings together to redirect the flow in the fuge. When I left the aquarium to get the parts, the PH was at 8.15 as seen in this screen shot below.
As you can see, 8.15 on the right but last night at 1800 it was all the way down to 8.08 to 8.09 and this is with the lights on. This is not normal.
So I went into my closet where I have all the aquarium stuff and found the fittings I needed and fitted everything together and when I came back I installed them on the fuge. Before turning it back on though, I got distracted with some other stuff and in only two hours, the PH had jumped up...
This may not look like a lot, but look how flat the PH stayed and once I shut the fuge off, this is what it did. It went from 8.15 to 8.21 without changing anything on the tank, without opening any other doors or removing the glass tops (which does usually cause the PH to rise slightly), the only change was stopping the flow in the fuge cutting it off from the rest of the tank. So I waited some more...
The PH went up all the way to 8.26!!! This is about as weird as it gets. The dips that you see on the right, lets explain those for a second... The first 8.26 spike you see, and then it drops. I turned the fuge back on! I left it on for about 5 minutes and it started rapidly dropping the PH. I turned it off and it started climbing back up. The second dip you see in there happened when I shut the whole tank down to do a water change. Just something that happens when water sits still in the sump.
Which brings me back to the fuge. I'm guessing I'm running about 20 gallons an hour through the fuge on average. Enough that it keeps the top of the water skimmed off but slow enough to not stir up the detritus that is in there. Which should be more than enough flow to keep the water from sitting and causing this issue, but I guess not. I will definitely be watching this very closely over the next week or so to see what it does.
As stated above, I have done two water changes in two days. I'm sure you are wondering why I did this since I rarely do water changes... The reason is simple... The algae in the main display tank and the fact that I have lost a lot of coral since I have been gone. All of my encrusting Montipora is dead. The red/green plating monti is just barely hanging on, but most of it is dead. The Pink acro birdsnest has been bleached out for a few weeks now with no polyp extension. Even my hammer was getting bleached out. So I was thinking that something had to be WAY off in my water.
I did a full run of tests, Ammonia, Nitrite, Nitrate, PH, Calcium and Alkalinity. Everything was within normal range with the exception of the Alk which was a little on the high side at 11. Calcium was 440ppm, nitrates were <5ppm, no ammonia or nitrites and the PH was right where my apex was showing it should be. It was at this time I decided to do two 15 gallon water changes.
I did the first one yesterday and I screwed up. Not bad, but it was still a screw up. I turned the pump on in the water, A Danner 1200 Mag Drive Main Pump. This is a BIG pump (okay, not that big but it is the largest physical size that I have) and it puts off a lot of heat which you really don't notice when it is in the tank. Although I do now since I'm running DC and my heater was kicking on more often after removing it lol.
Well the next morning when I was ready to do the water change, after leaving that pump on all night, the water was about 83ºF to 84ºF. This is not really hot, but is above my normal tank temp which is heater on at 77ºF and off at 78ºF. And it is still below the 85ºF where you start losing oxygen in the water. So it wasn't bad, but I knew it was really going to piss off things in my tank for a minute since I was doing a tank drain and fill rather than a sump drain and fill. My back didn't want to lean over like that and my lungs definitely didn't want to do it with all this coughing I have been doing.
I got that water change done, the tank heated up to about 79ºF after everything mixed together and everything seemed about as happy as it was. So I sat the barrel back in the kitchen and started making more water. I measured out the salt, filled up the barrel with water, put the salt in the water and put my little Maxi-Jet 1200 in there. Don't get the Maxi-Jet 1200 confused with the Danner 1200. The Maxi-Jet is a powerhead and the Danner is a main pump. HUGE difference. The Danner is 1200 gallons per hour, but the Maxi-Jet is only 295 with no head pressure. And more importantly, less heat buildup in the water. So I let this go over night.
The next morning I started doing everything above with the testing and water change. However, I noticed something different today. I can see polyps on the acro and I can also see some polyps on the plating monti.
The first pic and the second pic are of the same coral. The first one is just blown out with blue light. The second one is what the acro looks like now. And the third one is of the plating Monti. So something is doing something. I will be doing another water change next weekend when I get home if everything goes as planned.
So that is where my tank is at right now. I am starting to rethink my new sump design though after this. I was going to have the overflow water going into the sump be split 75/25 in the skimmer section / refugium section respectively. But I'm starting to think that may not be enough flow. So I may be going back to my original design of a large fuge in the middle with full water flow in it. Still thinking this one over though.