What fish-safe products for a tank background?

[travisty]

Hi there building a fish tank background.

have shaped foam to what I want with research all products used have been American not sold here. 
im looking for a product to coat foam a dry lock alternative 

a kind of hydraulic cement or something 

I need to cover the styrofoam hopefully paint outside but all products need to be fish safe happy to let products leach ect before fish get added

[EricL]

Hello @travisty 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about fish safe products.

I've just been in contact with Crommelin technical, and they suggest using the Crommelin Pond Sealer. However, they said that you can't use shaped foam or Styrofoam as it is not compatible. They suggest instead to use ordinary cement mortar to create your shapes and then covering it with pond sealer all around. 

If you need further assistance, please let us know.

Eric

[travisty]

Thankyou for the reply..

Chromlin was an option but I’m assuming you cannot apply colour over that,

I’ve also thought of using a concrete or mortar mix to apply over the styrofoam 

asking for options products fish safe 

should I use Portland cement or hydraulic cement,

I’ve heard possibly a tile mortar or pool grout.

My plan is to colour and detail with acrylic paint and apply a clear sealing coat once complete

 

[MitchellMc]

Hi @travisty,

 
I completely understand how challenging it can be to replicate D.I.Y. projects, especially when the materials and products recommended in tutorials or articles aren't available in Australia. It can be frustrating when you're looking for specific solutions, like a fish-safe coating for a tank background, and the products used in overseas projects simply aren't sold here.

Unfortunately, there aren't many specific, widely-recognised fish-safe coatings or cement products that are tailored for aquarium backgrounds here in Australia, and most of the recommended products tend to be from the US market. That said, the fishkeeping community in Australia is likely your best resource for finding locally available alternatives. Many fishkeepers have hands-on experience with creating custom tank backgrounds, and they might be able to point you towards suitable products that are both safe for fish and readily available in local stores.

As for your specific question about using Portland cement or hydraulic cement, these can both be used for creating backgrounds, though it's important to consider the curing process. For a fish-safe tank, you must ensure the cement is fully cured, and any chemicals have leached out before adding fish. Some members of the community might also suggest alternatives like tile mortar or pool grout, as you mentioned. Acrylic paints, when applied correctly, can be safe as long as they are fully cured before contact with water. However, you really want to use products that have been trialled and tested rather than navigating in the dark and guessing as to when harmful contents have leeched out. Regarding the Portland cement, I've found that "It must be cured for at least a month before it is stable enough to not cause changes in your pH".

To ensure you're on the right track, I'd definitely recommend talking to others in the local fishkeeping community for guidance on which products they’ve used successfully. 

Please let me know if you have any questions.

Mitchell