CLR !!! Calcium Lime Rust ?

[Glenner’sreef]

We’re all familiar with water deposits on the inside of our shower doors. You can’t scrub hard enough to get this stuff off. The go to product is CLR. But what is causing what looks like the same hard to scrub off film inside a tank? It’s a friend’s tank and thankfully large enough to really apply some muscle to it. Some of it does come off with a scraper blade and handle. My first and only conclusion was this. He does Alk 8.3 and Microbacter 7. It’s a large swim tank (150 gal). This beautiful tank should not have that hard film on the glass.

 

[T-J]

Without pics it's hard to guess. Is it possibly coralline algae? Is it pink, purple or green?

 

[Glenner’sreef]

Sorry TJ no pics. Definitely not coralline. It’s a hard chemical deposit all over the inside of the tank.

 

[T-J]

The only other thing I can think of is to check the alkalinity. I get a white deposit where my dosing pump line for alkalinity rests. It forms a hard, white deposit on the side of my sump. Pretty easy to scrape off though.

 

[Glenner’sreef]

So this is very evenly across all of the inside glass. If I had to say, it reduces the clarity of the tank glass by 5%. That being said. It’s noticeable to the human eye.

 

[T-J]

So this is very evenly across all of the inside glass. If I had to say, it reduces the clarity of the tank glass by 5%. That being said. It’s noticeable to the human eye.

Is this person dosing alk/calc directly into the display? What's the current alk and calc numbers. If it were my tank, I'd start there.

 

[Glenner’sreef]

Great idea

Is this person dosing alk/calc directly into the display? What's the current alk and calc numbers. If it were my tank, I'd start there.

Is this person dosing alk/calc directly into the display? What's the current alk and calc numbers. If it were my tank, I'd start there.

He’s not dosing cal./alk like a 2 part. He’s only dosing the Microbacter 7 and Alk 8.3. It’s a swim only tank with large tangs, Angels etc. Microbacter shouldn’t be hurting anything. But I was concerned that long term Alk 8.3 might be causing this hard film.

 

[Randy Holmes-Farley Verified Community Expert]

We’re all familiar with water deposits on the inside of our shower doors. You can’t scrub hard enough to get this stuff off. The go to product is CLR. But what is causing what looks like the same hard to scrub off film inside a tank? It’s a friend’s tank and thankfully large enough to really apply some muscle to it. Some of it does come off with a scraper blade and handle. My first and only conclusion was this. He does Alk 8.3 and Microbacter 7. It’s a large swim tank (150 gal). This beautiful tank should not have that hard film on the glass.

In addition to coralline, it may also be an identical material to you shower: calcium carbonate.

What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com

 

[Randy Holmes-Farley Verified Community Expert]

But I was concerned that long term Alk 8.3 might be causing this hard film.

It's an alkalinity additive like any other. Getting some calcium carbonate is normal.

 

[Glenner’sreef]

Thanks Randy, I’m just super picky about the clarity of my own tank that I feel this guys pain when it’s less than perfect.

It's an alkalinity additive like any other. Getting some calcium carbonate is normal.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks Randy, I’m just super picky about the clarity of my own tank that I feel this guys pain when it’s less than perfect.

The ways to reduce it are:

1. Stop all efforts to boost pH.
2. Stop dosing alk for a bit and let it decline.
3. Reduce pH by switching to a low pH alk mix like sodium bicarbonate, or a calcium organic such as Tropic Marin All for Reef.
4. Ensure magnesium is normal to high.
5. Keep organics and phosphate on the high side.

After a few days of not dosing alk, restart slowly, adding additives to a very high flow area so it mixes in fast.

 

[Glenner’sreef]

Very nice, will do. In my many years in the hobby, I’ve never come across this. This fellow and his wife are good people. He has cancer, I’d like to help him out.