Used kitchen/bath silicone.

This is another thing which confuses me because there is algae/fungus growing on that silicone so it makes me wonder if the mold preventative they add is just a blatant lie. On the other hand I used door/window silicone in my bathroom and it has no mold growth what so ever. I'll try to get a pick of it and upload it when I get home.

To confuse me even more is that this problem started in 2010 in my old tank that didn't have any "mold preventing" silicone in the sump.

 

If you think the silicone is an issue, replace the sump and take it out of the equation. A 20 gallon is on the small side for a 125 anyway. Do you have a refugium in the current sump?

 

Honestly I want to eliminate any other possible problem first. If nothing works and it does come down to changing the silicone that's going to suck because I can't pull the sump out so it would have to remain in the stand while I work on it. And then I have to worry about what will happen if I remain sumpless for a few days while it dries. I can live with the coral dying but losing fish would suck even more. And if it comes down to it I can always have a fish only tank with never growing corals, Lol

 

Ah, I see. Originally I had the sump under my 125, but got tired of it being crammed under the stand, so I moved it to the basement.

One thing I didn't notice on your equipment list, how do you do top-offs?

Also, what temperature do you run the tank at?

 

I run the temperature at 78. Top offs are done automatically via a float switch and a 34 gallon trash can in the basement that pumps water up through the floor and into the sump.

 

Does the trash can have a lid on it????
Check the tds on the topoff water.

 

From what I've read from reputable people, on other boards as well,
Silicone should dry for WEEKS, not days.

The GE 2 has an acetone based curer, etc.

As Barbinj stated, it is usually b/c the silicone has not completely cured/dried.

For a 1/4 inch bead, I think they recommend 7 days for aquarium use, and IMHO, that is not even long enough.

I'm about to silicone a C2C overflow into my 180 with RTV 100 series, and I'm still going to let in cure/dry at least 2-3 weeks before it will even see a FW test!

Good luck

 

It has a lid on it but there is a hole drilled in it for the pump extension cord. I just tested the tds and it reads 4 but it still smells like plastic in there. Do you think I should still get the food safe brute just in case? Or if there was anything leaching in the tds would be much higher?

Im not sure if it was the GE brand. It was picked up from walmart and I'm pretty sure it was bathroom silicone. It wasn't the acetone cure because it smelled like vinegar just like the aquarium stuff .

 

You can't go by smell. I'm still placing my bet on the silicone type.

 

I also just tested my ph with an Api kit and it's in the brown color range which is 7.8-8.0. I can't tell exactly which shade of brown it is. My ph probe reads 7.99 but I'm pretty sure that needs calibrating.

I will test my nitrates when I get home tonight. Phosphates I know will be undetectable because of the gfo. I'm still getting ugly algae on the sand bed though for some reason and it comes back just days after I siphon the sand bed.