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Discussion Starter · #1 ·
After several coats onto the viv background do you have to waterproof the cement? If so what are some animal safe products? I was thinking a marine grade epoxy? Is this a god idea or should I look 2wards another another product?
 

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You don't have to seal cement necessarily. If you cure it properly you don't need to use a sealant. You can use something like a marine epoxy to coat the cement which will mean you can use the viv sooner. It seems like about a month of soaking/spraying the cement background is enough to consider most backgrounds cured.

Keep in mind that some sealants won't completely water proof it (like most acrylic sealants) and just prolongs the curing process.

There have been a couple good threads on cement curing recently that are much more scientific than what I just wrote. Try searching using a combination of "cement, curing, concrete, grout" etc. I'll see if I can find any.
 

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yes an epoxy will seal it, but it will be very expensive.


i have shopped around, most marine epoxy run $150+ for a gallon (to cover 250 sq ft, which is alot).


I believe many members, myself included, buy USComposites 635 epoxy as for the price it is the cheapest I have seen.

Epoxy : Epoxy Resins and Hardeners


You can buy the 2:1 or 3:1 both should work, they just have different curing times/temps (see the faq).


I paid $93 for a gallon of 3:1 shipped to my place....not cheap, but cheaper than marine epoxy from a yacht shop or w/e. I know others have used drylok, but in my experiences it is not strong enough for constant waterflow


the only reason you need to seal your cement is because it will leak and change the PH of your water. As parkanz said, if you soak it in vinegar/water baths for a month you will pull most if not all of the leeching chemicals out of the cement and won't need the epoxy.

Basically it comes down to $100 or 1 month wait time and some vinegar baths; whichever you prefer.
 

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You need to do a search on this. I had a similar thread at one point. The cememnt does not "leak" to change the ph. It only chanes the ph of the water if it is not fully cured. Its the freelime in the concrete that raises the ph of the water if not cured properly. Also, vinegar IS NOT the way to do this... trial and error i found this out myself. Vinegar eventually just errodes the cement, and the acidity of it doesnt do anything to help the curing of the concrete which is the root problem. Carbon dioxide is what cures free lime. The technique is to get some dry ice and seal it up in a container with your concrete and t will cure much faster than if left in open air. There is a previous thread with info from another member that seemed to be more of an expert at this than myself if you ue the search feature.
 

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I used drylok on my DIY background for my dart tank and my African Cichlid biotope. I think it was almost $8.00 with tax. My dart tank has only been set up 4 months but my African Cichlid tank has been setup for two yrs with no deaths
 

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Discussion Starter · #6 ·
okay so i found some 5:1 epoxy left over from a project a while back. even tho its not marine grade it should work right?... lol there will be a part where it sit in the water completly and a part where water is constantly running over it. its this stuff brushable? i looks pretty think so idk if it wil be possible but im gunna run some practice runs on a small trial piece just to make sure.

ps thanks for everyones information and help its greatly appreciated
 

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okay so i found some 5:1 epoxy left over from a project a while back. even tho its not marine grade it should work right?... lol there will be a part where it sit in the water completly and a part where water is constantly running over it. its this stuff brushable? i looks pretty think so idk if it wil be possible but im gunna run some practice runs on a small trial piece just to make sure.

ps thanks for everyones information and help its greatly appreciated
Dude. You dont need to seal concrete.
 

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Discussion Starter · #8 ·
so a continous flow of water over the concret wont erode it at all? Its only brushed on concret and ive applied atleast 7 coats but i still feel that a sealant or something will be need to make sure it doesnt flake off.
 

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the concrete should not erode (at least not for any noticeable amount).

*my understanding*:

the only reason concrete is sealed by many users is to prevent the water pH changes which occur.

From my understanding, the best method is a SPRAY of vinegar (to "open the pores" so to speak) and then a WATER bath to accelerate the curing as much as possible. Again, as kgb said, this only happens UNTIL THE CEMENT IS 100% CURED. This DOES take some time, which is why people do baths/etc to speed it up.

On the other hand, you can just use an epoxy and "seal" it.....to emphasize: the sealing is not meant to keep the water/concrete separate; rather it is meant to keep the not-yet-fully-cured concrete from touching the water. There is a subtle but distinct difference. If the uncured concrete never touches your water, you don't have any water pH issues....and you don't have to wait weeks for the curing to "complete".


ONCE FULLY CURED, CONCRETE/CEMENT is PERFECTLY SAFE UNSEALED.



This is my understanding of it all...please correct me if I'm wrong as I don't have an in depth grasp of the science yet :)


EDIT: @HazedSHaman: Are you making the coats thicker each time? I haven't tried yet (just got my foam carving knife today...finally...) but from what I've read only 3-4 coats of increasing thickness are needed. 7 sounds like a lot!
 

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You need to do a search on this. I had a similar thread at one point. The cememnt does not "leak" to change the ph. It only chanes the ph of the water if it is not fully cured. Its the freelime in the concrete that raises the ph of the water if not cured properly. Also, vinegar IS NOT the way to do this... trial and error i found this out myself. Vinegar eventually just errodes the cement, and the acidity of it doesnt do anything to help the curing of the concrete which is the root problem. Carbon dioxide is what cures free lime. The technique is to get some dry ice and seal it up in a container with your concrete and t will cure much faster than if left in open air. There is a previous thread with info from another member that seemed to be more of an expert at this than myself if you ue the search feature.
I think you just interpreted my meaning of "leak" differently; I simply meant that any water running over the (uncured) concrete will have its pH changed by a reaction with the concrete (I was using the term "leak" here to mean the uncured freelime coming out of the concrete to interact with the water).


You are right about correcting me on the "vinegar bath" that was poorly written by me. I should have been clear: SPRAY vinegar, then BATH in water. I am inclined to believe you that a vinegar bath would erode away the concrete. However, I'm not entirely knowledgable on the science so I can't comment with too much conviction.

I'm very interested in the dry ice technique I'm going to have look up your thread....
 

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What about the Drylok idea? It is cheap, natural, and safe (unless more experienced people tell us otherwise).

"DRYLOK is a concrete and masonry waterproofing paint manufactured by United Gilsonite Laboratories (UGL). It is available in both latex and oil bases, and is tintable to a handful of different light and pastel colors to complement decor. DRYLOK forms a barrier against hydrostatic pressure---the force that water exerts against a surface due to gravity---to prevent water seepage through concrete. DRYLOK can be brushed or rolled on, and does require two thick coats to be effective. DRYLOK can only be used over Portland cement-based concrete, and is only effective as a waterproofer when used as the first coating over the bare surface."

More info: UGL - DRYLOK® Masonry - Masonry Waterproofer

One gallon of that stuff costs only about $9, and you won't need that much anyway since it is enough to cover 75 to 100 square feet of surface area.
 

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What about the Drylok idea? It is cheap, natural, and safe (unless more experienced people tell us otherwise).

"DRYLOK is a concrete and masonry waterproofing paint manufactured by United Gilsonite Laboratories (UGL). It is available in both latex and oil bases, and is tintable to a handful of different light and pastel colors to complement decor. DRYLOK forms a barrier against hydrostatic pressure---the force that water exerts against a surface due to gravity---to prevent water seepage through concrete. DRYLOK can be brushed or rolled on, and does require two thick coats to be effective. DRYLOK can only be used over Portland cement-based concrete, and is only effective as a waterproofer when used as the first coating over the bare surface."

More info: UGL - DRYLOK® Masonry - Masonry Waterproofer

One gallon of that stuff costs only about $9, and you won't need that much anyway since it is enough to cover 75 to 100 square feet of surface area.
Many people in the aquaria hobby do use Drylok successfully. I personally have tried and will not use drylock (for THIS purpose, it has many other great uses!) because, in my opinion, it looks very fake when it dries whereas the cement mix (i use precision grout actually) dries to a much more "stone-like" finish.

In terms of "safety" only ignoring the final look....I believe it is safe as many have used them in complete submersion without problems
 
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