High Alkalinity

[joyski58]

I am looking for suggestions. I have extremely high alkalinity -- off the chart high. The chart ends with a listing for 15 drops of test solution, and my tank is registering 19-21 drops of testing solution before the test water turns from blue to yellow. My calcuim is 460-470ish. pH was 8.4 last time I checked. Magnesium was a bit low. I've lost colt coral, zoos, a clam, mushrooms are small, and more than half of my devil's hand isn't extending, blastos are shrinking, yellow star polyps are fading away ... The only thing that looks good are 2 rose tip anemones and my fish. I use Tropic Marin salt and do 20 gal water changes about 1 time per month. I use RO/DI water that I make for top off and I buy change water from the reef shop. I've tested all water involved, even my ER tank water, and the only water that tests high is my display tank. I have live rock, and a live sand bed that's no more than 2" deep at the deepest. I have a Remora hang-on protein skimmer, a wet/dry filter w/live rock in it, and a 15 gal high refugium plumbed in between the tank and wet/dry. I have 1 large tunze powerhead on one side and 2 nanos on the other, on a controller, as well as 1 reg power head. I've never been able to grow coralline algae. I have an over-abundance of tiny brittlestars, no real algae issues, although I get some cyano. The tank's been set up since probably 2005. Anything anybody?

[AwkwardParrot]

How old is your test kit? Brand?
How big is your system? (Guesstimate water displacement by rock/sand)
Do you dose? If so, what?
Do you run any media?
Do you ever clean the wet/dry?
Do you have large temperature swings?
You could see a swing because of light, are other parts (wet/dry filter, fuge) lite?
The salt you are using, has almost nothing in it; so you can dose to desired levels. You can do a large water change (50%) and it may come down.
Coraline will grow when Alk is down and Mag is up, as long as PH and Calcium are ok.

[joyski58]

My test kit is new and is by Aquarium Pharmaceuticals. I'd say there's 85 gallons of water total (72 display w/rock + 15 in refug + 7 in wet/dry). I've recently dosed Seachem reef advantage magnesium and zooplex, but nothing else. The wet/dry was recently cleaned and I switched from bioballs to live rock and it was suggested by the reef shop owner that I keep it half covered with water. I always suck out all the water from the wet/dry during water changes. My temps are pretty constant; I have an inline heater, and temps run from 78-80. I've never seen temps over 81, even in the summer. I have a RayTec Mini Temp lazer gun, which is really accurate. The salt is Tropic Marin's Pro-Reef and the box says "pharmacutical grade especially for modern reef aquaria" and has quite a list of ingredients. The reef shop owner feels it the best and I shouldn't need to dose as long as I do frequent water changes. What would you suggest?

[joyski58]

Oh, yeah. I've just recently added carbon to the system on the suggestion of the reef shop owner, and I've always used packets of Algone for algae control. Refug is lit, but wet/dry is not.

[W8lifts]

Make a small batch of fresh SW and test that to see if it is the salt mixture

[IslandCrow]

You may want to take this over to the chemistry forum. From what you're saying, this doesn't make a lot of sense, but Randy, Boomer and those guys may have some idea. If I understand correctly, you've tested your SW for your water changes, and that has normal alkalinity levels. I can't think of what else would be making your tank water more alkaline if you're only adding magnesium supplement and zooplex. My only guess would be the carbon, but I don't even know if that's a possibility.