120 G Mystery

[Donmarco]

Last July I moved from upper Montgomery to lower Charles County, Maryland. Getting my 120G reef tank down here was a real chore, but after a lot of work (and the total replacement of the live sand, yet keeping the LR and everything else) I had it back up and running. I did lose several specimens (coral and fish) and overall I felt lucky that I still had the tank. I lost a large birds nest coral, but fortunately I saved a half dozen frags, which are growing very nicely. In a year or two I should have five or size show pieces.

 

Now it's 7 months later and the tank is doing very well. All the coral are thriving, the fish are healthy and the tank is the showpiece of the neighborhood. Children and adults even stop outside my window to "ooh" and "ah" at the sight of it.

 

Still, I have a couple of things

[zygote2k]

Here's an easy answer for alkalinity-

Test weekly and dose daily. If the alk drops x amount per day, dose that much every day and measure at end of week. Adjust daily amount up or down as needed. DOSE DAILY.

[davelin315]

First mystery - what is your calcium dosing regimen? If you overdose calcium, your alkalinity could drop so that could be a factor in it. Describe your system a little bit more - I imagine you are using either a calcium reactor or calcium supplementation due to the sps you have, so that could be the basis for your problem. All of my top off water is limewater, is that what you're using as well?

 

Second mystery - are they particulates or microbubbles? Sometimes the two can look awfully similar and it's difficult to determine what they actually are without taking a sample from your tank and letting it sit without any movement. You can turn your pumps off temporarily and see what the particulate matter does - if it sinks, then you know there's something allowing detritus to get stirred up in your water column. More likely, given that you use a skimmer and some sort of filter material/filter sock, it's microbubbles and they will float to the surface when the pump is on. The solution for this is to troubleshoot where they are coming from. If the water from your skimmer has lots of bubbles, I'd suggest putting a filter sock at the end that is partially submerged in the water. This will allow some of the microbubbles to combine and float to the surface. You could also arrange your sump so that the discharge is far from the pump to prevent as much air as possible from entering the pump. On the other hand, if they're air bubbles, you could also have a small hole somewhere that is causing a venturi to take place, or your pump may simply be sucking in air from the surface of the water and shredding it as it passes by the impeller on the way to the tank.

[Gatortailale]

Yes- agree with Dave, we need some more details on system. Do you use calcium reactor or drip Kalk? Sounds like you have lots of corals. Thus, they are going to demand trace element supplements as evidence by their use of the dosing you have been doing. Initial cost of calcium reactor or kalk drip system is of some concern, but in long run you will use less of a 2-part dosing with one or both equipment additions.

 

Time of day you do your testing can also impact numbers. It's good to focus more on alk to determine system balance as I have found over 10+ year that ph swings up and down depending on of lights on or not.

[FearTheTerps]

Have you cross checked your test results with another testing kit? thats the first thing I would do.

[Coral Hind]

I agree with Terps, double check the test kits as they do expire.

 

I would also check out SMMAS.org and have a local reefer check out your tank.

[Donmarco]

Describe your system a little bit more - I imagine you are using either a calcium reactor or calcium supplementation due to the sps you have, so that could be the basis for your problem. All of my top off water is limewater, is that what you're using as well?

 

No, the arrangement in my new home is such that there isn't room for a calcium reactor, though I do own one and used it on the same tank when I lived in Montgomery County. Instead I test CA weekly, and perform regular water changes (10 G at a time). CA seems to remain stable, so I do not dose it unless it falls below minimum target. Nor is it high and there is little fluctuation in CA presently, though I keep an eye on it. My regular tests of water parameters hasn't prompted me yet to dose, only to monitor and continue to observe. Only ALK fluctuates. Below my tank I have a 35G Zero-Edge multi-comparment sump. Water flows into the sump from the rear, left and right. On the right water flows from the tank into a refugium stocked with live Fiji mud and chaeto. It flows toward the opposite end, meeting the overflow from the left side of the tank, flowing through a filter sock. The water flows toward the front left and is pumped into a AquaC protein skimmer. The water returns from the skimmer into the same compartment. Water then flows to the right front of the sump, over a filter sponge that is in place to reduce micro bubbles, and is returned by a pump to the main tank. I don't use limewater for top off. Instead, for the past four years, I've used RO water.

 

Second mystery - are they particulates or microbubbles? Sometimes the two can look awfully similar and it's difficult to determine what they actually are without taking a sample from your tank and letting it sit without any movement. You can turn your pumps off temporarily and see what the particulate matter does - if it sinks, then you know there's something allowing detritus to get stirred up in your water column. More likely, given that you use a skimmer and some sort of filter material/filter sock, it's microbubbles and they will float to the surface when the pump is on. The solution for this is to troubleshoot where they are coming from.

 

Actually, the particulates are solids and not microbubbles. I do see bubbles in the water from time-to-time as the return pump in the sump does sometimes suck up air. The materials suspended in the water are solids, some of which might be detritus, but I do not think all of it is. I've checked the tubing, connections, etc. and cannot find any problems. I don't know what might cause detritus to become stirred up in the water column. There are four return water fittings at the rear of the tank, but these are pointed toward the front and sides of the tank and not toward the sandy bottom. I also have two Vortech pumps, one on each side, but these are near the top of the tank and the wave-making action is set low, in lagoon mode, not tidal crest mode.

 

Thanks for the advice. I'm open to suggestions.

[Origami]

What is your magnesium level? Low magnesium can make it difficult to maintain supersaturated levels of calcium and alkalinity. Particulates could be suspended calcium carbonate precipitate.

 

Nominal magnesium level is 1280 ppm. Some people run it a bit higher, too.

 

I'm assuming that the "1.6 ppm" and "2 ppm" figures given in your original post are actually in units of milliequivalents per liter, or 1.6 and 2 meq/l.

 

While you're at it, tell me what your calcium level is, too.

 

Consumption is also a possibility, depending upon how many corals and other calcifying organisms you have.

 

Alkalinity drop is always noticed first because it looks like it drops the fastest. This is because, nominally, 20 ppm of calcium is combined with 1 meq of alkalinity to form a milliequivalent (50 ppm) of calcium carbonate. Thus, while your calcium drops from, say, 420 to 400, alkalinity may drop from 3 meq (8.4 dKH) to 2 meq (5.6 dKH). The proportional drop in alkalinity looks much greater to the hobbyist than the decline in calcium.

 

Also, what do you dose to supplement calcium? Alkalinity? Do you test/dose magnesium? How often do you perform water changes?