Water tests and what they mean to me

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Milka coral

11/28/15 Performed water tests at 1 a.m. specifically because I spotted some STN in my tank all of a sudden.

Temperature late at night read 78.1 °F
Looking at the temperatures recorded by the Apex recently, I had a significant swing due to our weather change over the past 48 hours or so. The low was 77.1°F and the highest was 80.6°F, which is roughly a 3.5°F swing and more than I usually would allow. Maybe this is why three corals are reacting. Not sure, but it's definitely a consideration.

pH measures 8.26
pH varies daily, but the average reading is 8.04 to 8.35 daily.

ORP reading display 285
ORP measures dissolved oxygen content in the tank. Apex data shows the average is 287, with the normal high at 301 and the low at 269. I haven't cleaned this probe in a while, but these numbers aren't a concern.

Alkalinity 12.5 dKH
With some white skeleton showing, my first reaction was "What is the alkalinity level right now?" but it wasn't low at all. If you'll recall about two or three months ago it was crazy high, and double tests indicated it was around 21 dKH. I let it come down to around 16 and stayed there a few weeks, then lowered it to around 12 for the duration. I'd prefer it to be around 10, but I didn't want to rush it and cause coral issues. Seeing that the alkalinity is still at 12.5 dKH makes me wonder why some corals are turning white. The LPS look normal. The anemones look fine. The fish seem unaffected, naturally.

Phosphate measured .25ppm
Some phosphate in my system isn't surprising, and this amount isn't a concern. It was barely pale blue on the Salifert color chart. Yes, I'd like it lower and Phosphate Rx will pull it down once more. I'll hold off a couple of days while these corals are acting up though.

Calcium reads 425-450ppm
Calcium levels are good. My measurement was made with an Elos test kit, and one drop was a sputtering half drop, so that's why I'm not committing to 450ppm. It's probably about 425ppm or so.

Magnesium was tested twice, and measures 1250ppm
I'd added a gallon of Magnesium to my reef about two weeks ago, which I discussed in my previous blog. I was told I'd have to add four gallons to get the levels up to the number I desired. Interestingly, I've seen coralline appear on the glass quite a bit, and have been scraping it off to keep things clean. The Montipora species are big, growing fast and are each the color they should be, other than the one semi-shaded one I mentioned at the beginning of this entry. Only yesterday I'd noticed how three large 'caps' are all growing into each other due to lack of space. I need Magnesium to be higher, so I have the Icecap doser adding 99ml of solution every hour until the 1g jug is consumed. This will take a couple of days.

Nitrate was low at 3ppm
I actually expected this number to be higher. My reef has a refugium, liverock and a deep sand bed. I dose Prodibio every 15 days. Water changes are hit or miss; it's been at least two months since the last one actually. My nitrate kit is old, so maybe it's giving me a great reading. I'll have to replace it and see what it measures in comparison. But I won't lie, I liked the low number I saw tonight. 

Salinity was tested several times, and measured 1.024sg
I'm going to add some saltwater to the reef instead of freshwater (RO/DI) to help bring this number back up to 1.026sg where I normally keep it.

Anything new or changed? I added a green polyped toadstool leather to the tank last Saturday. One person told me he had problems with SPS when he had a toadstool in his reef, noting that when the leather shed, that stuff landed on his corals and caused die-off. I used to have a massive Toadstool in my 280g with SPS corals, so I'm not really sure what to think about this person's warning. Other than that, nothing else comes to mind that could be a factor. I'll update more if/when I have some additional information.