jaddc

I know, right? That's what I thought. I hope this comes up in pub quiz!

+1 FWIW

:-) Have to spread the knowledge!

Just saw an interesting video on the topic and learned something new. Passing it along:

Oh, I can believe that your standard is drifting. Evaporation and precipitation would be your main culprits. I would proceed just as you are doing.

Don't know about the product -- though its interesting. FWIW -- If you mix GFO:carbon in a bag at a 1:2 ratio, then the GFO won't clump up on you.

A refractometer is linear measurement tool. An analog thermometer is also a linear measurement tool. The liquid in a thermometer travels the same distance from 20-30 degrees as it does from 60 to 70 degrees or 100 to 110 degrees (measure it with a ruler). To calibrate a thermometer at the factory you pick two points (used to be water freezing and boiling in the old days) and then divide the distance between those points into even parts, or degrees. That scale is printed on the shaft and cannot be adjusted. And so once calibrated, the thermometer does not need to be calibrated again. If you take 10 liquid thermometers of the same make and model, you will see that the scales are slightly different on each one. It is similar for a refractometer. At the factory, the device is calibrated and they print the scale onto the view finder. That is why analog refractometers are technically never calibrated, only zeroed, by the consumer. If you zero out a refractometer (which you should do every time you use it because the prism can move) and then measure a standard solution, it should be dead on with no further adjustments needed. Often it is not the case with hobby grade devices because it may not have been calibrated properly, constructed properly, handled properly, etc. If a properly zeroed refractometer does not read a standard solution properly after the temperature has matched, then the refractometer is defective. One option is to buy a new refractometer. Another option is to zero the device, not at zero with RODI, but at the reading you are interested in. That is where the standard solutions come in (they are standard solutions, not calibration solutions). If you move the scale to read 35ppt when a 35ppt standard solution is in the refractometer, then you minimize the error in that local region. Obviously, this is a cheaper method than buying a good refractometer. Here's a home recipe from Randy: http://www.reefkeeping.com/issues/2004-06/rhf/

Yes, they could. They have the right to ask for licensing fees as well. Fortunately, I think they realize that that decision would go over as well as suing a 14 year old for downloading an MP3 without paying for it.

My probe likes Al Green.

+1 I'm not sure why they tell you to submerge, perhaps it is to insure that the probe is never exposed to air. But a WC is a great time to calibrate the probes anyway. In the lab, I only submerge the bottom 0.5 - 1.0" of the probe. The business end is the bulb at the bottom and that needs to be completely submerged and moist at all times.

Ah -- dunking the entire probes solves that problem of salt creep. True enough -- you did pay to see the number. :-) Unfortunately, that means calibrating frequently. Even the professional high quality probes are not able to hold calibration for very long.

100% correct. If you don't preemptively protect yourself in this country, then big business will come down hard on the little guy as soon as there is money to be made. I'm guessing the fine line between wild caught and captive grown is a result of the same system.

I use pH meters when I'm doing my (evil-mad) science in the lab. For your measurements, the probes are essentially the same (8.06 ~= 8.1 and 8.26 ~= 8.3). I doubt you can get better precision than that without driving yourself mad in the process. Plus the probes are not the same -- and I would trust the lab quality more than the hobby quality. It doesn't quite matter what the exact pH of the tank is (as long as it is within a good range), rather we are looking to guard against pH drift. And to measure a change in pH, you don't need to be concerned with a difference between the probes, just the difference in readings over time. If your probes are always 0.2 off from each other, then all is good. If not, then you have an issue. In the lab, I calibrate my probe frequently, because there are many many factors that influence precision and accuracy. Here is a video that demonstrates how to use a pH meter properly. While obviously you are not using a pH meter, pay attention to how he works with the probe. The key point is to rinse the probe with fresh RODI water when moving between tank water and calibration solutions. Tank - RODI- Cal1 - RODI - Cal2 - RODI - tank. Also, use tissue to carefully dap off all droplets of liquid if you want to reuse your calibration solutions. If you don't reuse the calibration solutions, then don't worry about that. Frequent calibration and proper probe treatment is key. No need to discard calibration solutions -- they should last a year before you should swap them out if you dry your probe before you dip it in and keep the container tightly sealed. One final point, keep the probes clean of salt creep.

You probably won't get enough of a vodka dose using the ATO only -- unless your ATO was like 75% vodka. I have some vinegar in mine, but not enough to affect my N's and P's.

Thanks! I really need to do an update -- my corals have been growing like crazy! Yes, exactly. I have my dosing pump elevated so that it only draws from the clear liquid. When I refill the container, I turn off the ATO for a few hours to let the excess kalk settle out.

I'm using the BRS Kalk powder. 60ml = 1/4 cup.

1. It is next to impossible to measure the pH of pure water. Your readings are most likely artifacts. 2. Your tank's pH is unlikely to be affected by top off water. Your tank is buffered against pH changes. If your tank's pH changes a lot then your problem is most likely with the tank water chemistry. 3. Why do you have to produce rodi that way? Was your DI resin depleting too fast? The best way to measure the quality of rodi water is via a TDS meter.

Yeah - I found it to be a cool way to explain the balance that we spend money to achieve in our tanks.

Food for thought.

Seal it in with epoxy?

Hmmm. Good question. I agree about the Fl rock -- mine definitely upsets the N:P ratio. I had it under control and then I re-scaped a while back when I moved and cut some of my rock to size. My phosphate problem started all over again. Took a couple months of aggressive GFO, but all is good now. Basically any rock near river/farm run off will be a phosphate sink. Reef rock from reefs (which I suppose is not the environmentally friendly way to go) would be best since phosphate levels are lower.

LTAs need a deep sand bed, right? You can try a PVC pipes or make a rock fort with deep (3-5") sand.

I'd guess that is because nitrogen is always bio-available thanks to the bacteria. The problem is that there is a natural buildup of inorganic phosphorous compounds in the rock. The phosphate content of your rocks depends on the source of the rock. If you "cook" the rock, you get rid of the organic phosphorous, but the inorganic phosphorous is still there. I believe a common form is apatite which is calcium phosphate. It stays there until it redissolves in the water (I think that is quite slow -- not sure) or bacteria or fungus consume the inorganic phosphate and then release bioconverted organic phosphate into the water. That's why I usually recommend to not run both at the same time. Run the bio-export for soluble N and P until the levels stop decreasing and level out. This sets the export ratio equal to the input ratio. What I have done successfully in the past is use chemical filtration to remove the excess. BUT as soon as the excess is gone, I stopped the chemical filtration before the N:P ratio will be out of whack again and the battle restarts.

Oh no Laura! Your tank is so beautiful and awesome -- I hope you get this problem fixed so you can enjoy it more. Rob is right on the money about the lights. I don't have the experience of other reef keepers, but I am a scientist so I look at these problems from the molecule point of view. Here's my logic on how I would approach this if I had your tank. 1) Your system is huge. So water changes is a rough way to go. That means you need to export the nutrients. 2) Chemical export is expensive for your system size. It will also be a lot of work to keep exchanging the stuff. 3) That means you need a biological export that fast growing to use up the phosphates and nitrates. So here's what I would consider as solutions. 1) Upgrade the refugium for more volume to grow more. The lighting is key and I would do some reading on hydroponics and indoor gardening. I would get the grow lamps that nurseries use for indoor growth and put it on the same timing that the pros use. You can use reef lights, but I think grow lamps are a bit cheaper. Of course, algae and plants are different but photosynthesis is a shared evolutionary trait. It has been known for a while that these machines are tuned for a light cycle called the circadian rhythm. If the lights are on 24/7 that rhythm becomes out of sync and causes death. Anything more than 16 hours is bad for this rhythm. I would shoot for 12 hours since that is the light cycle at the equator. In the larger fuge with awesome lighting, I would grow a variety of algae for diversity. 2) Biopellets. The easier version of dosing where the pellets serve as a food source for pelagic bacteria that use nutrients. A good skimmer then removes the bacteria. 3) Algae scrubber. Requires more equipment and labor to scrape off excess algae. Here is how I see nutrients. It is not the excess but the imbalance that is the problem. (search for the redfield ratio as an example) The exact numbers of the nutrient ratio are the source of many nerd arguments at science conferences (and it is different for different organisms), but the premise is true. So if you pull out all phosphate and you still have a ton of nitrates, then you still have huge problem. If the nitrate and phosphates come from biologics (feeding or death), then we need to export them using biological sinks (algae or bacteria). If the phosphate comes in from leaching, then chemical export is appropriate. If those two mechanisms get flipped, then the ratios get off and then there will still be issues in the long run. Hope that helps and good luck.

I would think the money is made on the replacements. And the replacements is really where all the expense is. Not only is there materials cost and production cost, but QA/QC would be a big issue. If 1 out of 10 discs failed, or worse, then you would have some angry customers. The main housing is all "off-the-shelf" engineering that's been around for a while. Aside from the limited life of fluorophores, I think it is the exposure to saltwater is another huge factor in the life-span of the discs. I doubt you can take it out of the water once it gets wet.