Excessive 2-part consumption
 

Brace yourselves, this may be a long one.

I set up my "new" tank about a month ago. I moved a while back, and everything has been living in 4 horse troughs for months. Last month I finally got around to getting the new tank properly situated - it is a standard 125 gallon, with a trigger ruby 36 sump and a 20 hex refugium, so let's assume maybe 160-170 gallons total volume.

I have a pretty shallow sand bed of about 1", composed mostly of brand new aragonite. Salt water was made from Oceanic (been using it for 10+ years) and 0TDS water (just changed all filters and the membrane, but that's probably neither here nor there).

About 120lbs of live rock was moved from upstairs to downstairs pretty rapidly, so I basically experienced no cycle of note (I hit maybe 1 nitrate, maybe). Contents of the tank is a few monti frags (cap + danae) totaling maybe 10 square inches, a half dozen Green Bubble-Tip Anemones and a medium sized patch of GSP. Nothing that you would normally think of as a calcium sink.

Parameters on the first weekend were pretty much as I would expect for Oceanic - high calcium (~470 or so) and low-ish alk (just under 7). I did what I would normally do, which was to take care of the alk over the course of a week, at which point the plan would be to dial in my dosers and celebrate a successful tank move.

At the one week mark, alk was about 8.6 (so far so good), and when I tested calcium (which I hadn't really tested at all, because previous experience told me it would be fine) was... 370. So I re-tested and it was still 370 - a drop of 100 in a week with close to nothing in the tank. Unusual. So I then did my best to bring up calcium over the course of the next couple of days, aand my alk is now <7. My pH, which I don't normally pay that much attention to is struggling to even approach 8.

Over the last 2-3 weeks that's been the general struggle - desperately trying to mash enough 2-part into the system to keep calcium and alkalinity at "normal" levels (above 8 for alk, above 400 for calcium). I'm currently dosing about 240ml per day of each, which from past experience at this kind of stocking level is absolutely ridiculous. My current schedule breaks the day into 4 6-hour periods, dosing Ca, Alk, Ca, Alk for 4 hours at a time (on for 15, off for 15 oscillating) with a couple of hours of rest in between. I'm keeping up, but only just.

Other parameters seem pretty normal for a relatively new tank - magnesium is at a pretty good 1350, nitrates and phosphates have been undetectable for weeks, water is crystal clear and the tanks inhabitants (such as they are) seem absolutely fine. I've been running my pumps in vinegar every couple of weeks since it's pretty obvious that all this calcium is going to end up somewhere, but I'm not sure what to do/test/change at this point. The test kits (all Salifert) are testing newly made saltwater as I would expect, and the pH/alk testing seems to be in agreement that alk is generally a bit on the low side, and drops pretty rapidly as soon as dosing stops.

Thoughts would be appreciated.

Is the substrate solidifying? My first guess is that the calcium is going into some sort of abiotic precipitation. I might look for tannish buildups inside pumps, etc, as well. As a second thought, I check that the supplement is getting into the tank. People have been deceived by pumps that aren't working, although if you're using three completely separate pumps, that'd be a bit much to be believed.

No obvious substrate solidifying that I can see (and I have made concrete in tanks in the past, so I know roughly what I am looking for) - I will give everything a good poke this evening to check.

I have two separate BRS dosers dosing CA and Alk, I've triple checked that they are not running on to the floor (and the pH bounce when I know the alk is running is measurable, so at least some must be making it there). I just refilled a gallon container with calcium this evening, and alk is not that far behind so I'm as confident as I can be that the pumps are dosing at somewhere close to advertised levels.

I'm pretty sure that I am getting at least some pump precipitation because one of my main returns literally just crapped out and I had to run it in vinegar for an hour to get it up again. It was, of course, the one pump I was too lazy to clean this weekend (I did the others as a precaution, but didn't disassemble them because as stated before, am pretty lazy).

I had a good old poke at the sand bed and absolutely no solidifying that I can see. There is a fair bit of precipitation throughout the sump though. I'm going to increase flow (bless you DC pumps) tomorrow to see if that might help.

Dave

Okay, if more flow helps, that's great. Otherwise, you might need to change the dosing output location.

240ml per day is insanely excessive for a "new" tank.

if it were me i'd drop the dosing down to a moderate 60ml per day, test every other day for about 2 weeks and go from there.

if you can spread out the dose over the whole day, it would minimize any precipitation, and also increase tank stability

Is there such a thing as calcium degrading with age?

The only change I have made is using a brand new calcium o just ordered from BRS, and after 12 hours of my "regular" dosing the calcium has jumped up to 480, with alk sitting about where I want it at just under 9.

The old calcium was pretty old (potentially a year or more - I'm honestly not sure since it appeared during the move).

Dave

I wouldn't think a year old would effect it unless it was sitting a on shelf for a long time before you bought it. Storage could have been an issue with it too, Not being in an air tight container.. Is there a use by date on the package?

Well, scratch that. Calcium is back down to 400 again, so no magic fix from new calcium (not sure where that last reading came from). I've switched the dosing location out of the sump and reduced dosage somewhat, so we shall see where we are in a day or two.

Dave

Calcium supplements are fine forever. Some combined alkalinity and calcium supplements are organic in nature, and might degrade over time. The supplement will get a bit more concentrated as water evaporates, but that's typically inconsequential.

Well, backed off a little (to maybe 180 ml per day), left things for a couple of days.

Parameters are bloody awful. Salifert tests show under 400 calcium and under 8 alk. Went to my local lfs, and their red sea tests showed 350 and around 7. I know that's not catastrophic, but after a gallon each of 2 part in 2 weeks, it seems stupid low.

Any ideas what could be causing such massive precipitation in a new tank? Is there a possibility of stray voltage forcing calcium out of solution? Did the dust from the sand (which I did rinse, but there is always some) provide an ideal "seed" environment?

I'm open to any ideas before "massive water change weekend" kicks in.

Dave

Small particles of sand can act as nucleation sites. It's been a month, though, so that effect should be over. I'd switch to dosing baking soda (unbaked) and put it into the main display, and see how that goes.

Aand two questions...

1) If I'm using 2 cups of sodium carbonate per gallon, what's the right amount for bicarbonate?

2) Any old baking soda do? Never really needed to step outside of the BRS I'm a box before.

Dabe

It's ½ as much if you're using sodium bicarbonate. The low pH limits the strength of the solution. Any baking soda will be fine.

Plain old arm and hammer works great. I buy the big bags at walmart in the pool section.

Have a quick read through this:
http://reefkeeping.com/issues/2006-02/rhf/index.php

Bertoni suggests ALK recipe 2.

Thanks guys. As soon as the weather calms profanity removed down ill head to a supermarket, and we shall see.

I switched to a lower dose of baking soda last night, and it is way too early to say if anything has helped yet, but my pH is now unusually stable. like "is my probe broken" stable. I've had a blip of 0.02 in the last 14 hours (it dropped a little immediately after switching to baking soda, then stayed absolutely constant), and other than that it has been nailed at 7.83.

Not sure if this is baking soda thing, but I've never seen pH show literally zero variation for 12+ hours before.

Dave

Unless your dosing right next to your probe I would have to say its a faulty probe.

I had the same issues with my tank. Got rid of two parts and went with Cal reactor, problem solves.

Baking soda has a very small effect on pH, lowering it a tiny bit. The sodium carbonate supplement will raise pH noticeably. That might be the difference.

My pH has been hovering around 7.8 / 7.9 for the last 24 hours. I pulled the pH probe from my older apex and added it into the new tank right next to the old one, then re-calibrated them both to ensure I am getting accurate readings. I can live with 7.8.

I took the opportunity to do a pretty big water change today (60 gallons - about 2 hours of fun), and my parameters are looking pretty good, if a tiny bit high for me - 450 and 9.6.

I'm going to back off the dosing to sane levels for a while, and we shall see if baking soda does better for this tank than carbonate.

Dave

It'll be interesting to see how the tank responds. I'm not sure what was happening yet.

I'll do a bunch of testing this evening and see where things lie. Previously, when I backed off dosing by this much for over 24 hours, there would be a big noticeable drop in Ca and Alk. Hopefully not this time - pH is at least sitting pretty stable (at about 8 right now), so fingers crossed.

I will say that whatever the problem is, it appears to be occurring in the sump. There isn't that much noticeable precipitation in the main tank itself (and no sandbed hardening), but there is some pretty noticeable precipitation across any flat surface in the sump. I moved all dosing up to the main tank, and increased flow through the sump by about 30%, so maybe it is a combination of that plus baking soda? Just one of those? Neither? Science is hard.

Dave

That's not solving the problem.... that's avoiding it.

Calcium is at 460 and alk is at 8.6. I think I've been dosing about 80 per day of each, and it seems as though there is a little bit more alk consumption than calcium right now (although that's not accounting for carbonate vs bicarbonate, when I think about it).

I'm going to dial back calcium to 40, and see where alk is tomorrow before I turn that down any more, but parameters seem at least within spitting distance of being normal so that's good.

Dave