ORP dropping???

[BSJF]

ORP is 260s this morning.

Maybe all the spawning going on in the tank? Chromis, clownfish and who knows what else.

[Squiers007]

If your pH continues to be low, and you have corals in your tank, your growth rates for your hard corals will be greatly diminished. At lower pH it is much harder for the coral to precipitate the calcium carbonate from the water in order to incorporate it into there skeleton. I would seriously consider adding a kalkwasser drip or dosing by some other means. In addition, low pH can have negative effects on marine fish including decreased reproductive success. I'm sure Brad from GCreef could chime in and tell you more about the effects on marine fish.

[Europhyllia]

pH of 7.8 has been the normal forever. It does raise very slightly with all the lights on. I have a pinpoint probe, and also test with a test kit occasionally. I used to freak out about it, but I have accepted it. I do run a calc reactor and run my lights in the sump opposite. Yesterday, with the cooler morning we had I was even able to let some fresh air in, but the highest it got was about 7.85 in the afternoon.

Here's some info from my favorite pH source ;)

That the alkalinity is at least 2.5 meq/L, and preferably higher at the lower end of this pH range. This statement is based partly on the fact that many reef aquaria operate quite effectively in the pH 7.8 to 8.0 range, but that most of the best examples of these types of tanks incorporate calcium carbonate/carbon dioxide reactors that, while tending to lower the pH, keep the carbonate alkalinity fairly high (at or above 3 meq/L.). In this case, any problems associated with calcification at these lower pH values may be offset by the higher alkalinity. Low pH primarily stresses calcifying organisms by making it harder for them to obtain sufficient carbonate to deposit skeletons. Raising the alkalinity mitigates this difficulty for reasons that are detailed later in this article.

http://www.reefkeeping.com/issues/2004-09/rhf/index.php

[BSJF]

I love the reefkeeping articles, they have saved me many times over!

I used to drip kalk, then switched to the calc reactor a few years ago because I couldn't keep up with the tank demands. I'm now topping off with kalk at night in addition to the calc reactor, but since I don't evaporate much water I also have to dose two part which drives me crazy! I strive to keep the alk at the high end of normal, and calc in the normal range. Do better some times than others. There is only so much my brain can handle