7 year old reef tank high alk

[GeoSquid]

I have a 7+ year old reef tank and the alk is always high. It's all sofies and I haven added any buffer alk/ca in about a year and the alk is always 13-14 ish. I've tested my new saltwater and it's about 9. Only filtration is Cheto and calerpa. No skimmer. Ca is 420 and haven't checked mg in awhile. I used to have to 2 part but not anymore. Anyone have an idea why it's high and how to lower?

 

[Troylee]

I’d say testing error but if a new batch reads normal that kinda takes that out… do you use any ph buffers?

 

[Randy Holmes-Farley Verified Community Expert]

Do you dose nitrate? It adds alk.

In a low demand tank, very slow dissolution of rock and sand (which is typical) will slowly raise alk and calcium. It goes unnoticed in aquaria with higher alk demand, except that the sand very slowly depletes.

Tap water can also add alk.

 

[GeoSquid]

I'm not dosing anything and I use to do water. I have a large 8" clown trigger that was great for years then decided to start eating corals. So, my coral load is light for a 180 gal, mostly mushrooms, gsp and a couple bubble tips that stay super small now. The fish is awesome though, so I've kept him.

 

[GeoSquid]

Use only rodi wayer

 

[Randy Holmes-Farley Verified Community Expert]

In the trigger consumes coral skeletons, or chunks of calcium carbonate, they can dissolve in its gi tract and boost alk.

 

[GeoSquid]

Wow, really? Interesting. I had all soft coral though.

 

[Randy Holmes-Farley Verified Community Expert]

Wow, really? Interesting. I had all soft coral though.

Some soft corals have calcium carbonate spicules in them. Leather corals for example. But just sand will do it.

 

[GeoSquid]

Oh, I also have about 10 mangroves above the tank growing in tubs with the macro algae. Not sure if the add alk in some way. Just curious. Their pretty small.

 

[Randy Holmes-Farley Verified Community Expert]

Oh, I also have about 10 mangroves above the tank growing in tubs with the macro algae. Not sure if the add alk in some way. Just curious. Their pretty small.

I am not aware of such an effect. :)