# DIY rock background, questions on concrete...



## trantran (Jul 6, 2008)

im doing my first diy rock background, i got everything cut out. 
I did first coat of Quikrete Hydraulic Water Stop Cement , how long am I suppose to wait until I put on a second coat? till its dry? or 24hr?










this thing drys fast, I mist it with water to keep it from cracking. right now its dried is it suppose to be easily rub off? I mean i could rub it and it would start falling off. is this normal? i thought it would feel hard maybe cause this is the first coat. im worried it might chip off in the furture.

also is it bad if I leave any foam expose? like for the side of the rock that is touching the glass, do I concrete that too? if I do it would scratch the glass.


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## a_c_arnold (Mar 7, 2008)

Put on another coat whenever and allow that coat to cure. Go to lowes or home depot and buy Drylok concrete sealer and some black and brown concrete colorant. Use the concrete colorant to color the drylok and paint on 2 or three coats of drylok. The drylok is a great product and will make the cement background worth your time. I have made several DIY backgrounds, with and without drylok. The background without the sealer are **** and don't hold up well over time. The drylok will definately add life to your background and make it more durable. Look at my tanks, the 40 long was made with drylok. The stuff is great because you can't paint rocks or whaterver else you want and they will match your background.


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## trantran (Jul 6, 2008)

so do I just brush drylok with the old concrete?


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## a_c_arnold (Mar 7, 2008)

Drylok is basically like a really thick paint. At my local stores, it comes in white. I usually put a good coat of white on and allow that to dry. Then I use the black dye and color the drylok a very dark grey color. I apply a coat of dark grey for a base. Then bring in lighter shades of grey to give a more natural look. If you want you can do some shades of brown as well.


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## trantran (Jul 6, 2008)

can I use the color I have with drylok? also there are diff kind, theres oil base and latex or something...


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## a_c_arnold (Mar 7, 2008)

Additional info, sorry if I sound like a drylok rep, but if your a fan of the 3d backgrounds, this stuff is wonderfull. I haven't tested styrofoam by only painting it with drylock, but it would likely work just as well as the backgrounds made with cement covered in drylok. I like to have cement as well because it weighs down the styro slightly. Use lots and lots of silicone when attaching the background to the tank because the styro is very bouyant even if you use a lot of cement. The ultimate failure of DIY backgrounds is them breaking loose from the back of the tank after a few years of use. I am very weary of complex styro structures that have that have small sections attaching them to the background. I have read many horror stories on this site of pieces breaking off and floating to the surface. I have had my own pieces come free after 2 or 3 years as well. I have embeded large dow rods into my more recent designs in order to make sure this doesn't happen. It's also a good idea to attach the background flush to the top edging of the tank because that will lesson the strain on the silicone by countering its bouyancy.


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## a_c_arnold (Mar 7, 2008)

Get the latex based. Drylok is not clear and will have to be colored. I would assume that you could use any aquarium safe dye. I chose the concrete dye because I knew that it had been used multiple times in aquariums, but I'm sure there are many alternatives.


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## trantran (Jul 6, 2008)

ok for the conrete im using right now, can I use drylok as the last coat to seal it?

and why does the conrete flakes off so easily? did I do something wrong


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## a_c_arnold (Mar 7, 2008)

Here's a few things that I've done with this stuff.

























You can use cement and drylok for things other than backgrounds as can be seen by the last pic. You can do way more than I have depending on your patience and artistic level.


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## a_c_arnold (Mar 7, 2008)

I had the same problem as you with the flakey concrete. I just went with multiple layers of concrete and made sure to keep it moist as it cured for several days. The drylok can be used as the final coats and will really strengthen the finish. I wraped the drylok coat all the away around to the back of the background in order to make sure that the front of the background was sealed, thus making it less likely to flake off around the edges.


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## a_c_arnold (Mar 7, 2008)

I just noticed your top pick and question about the colorant. Your concrete dye is the same stuff that I used.


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## trantran (Jul 6, 2008)

thanks, im gona continue to use the the stuff i have. after that ill go pick up the dryloc


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## trantran (Jul 6, 2008)

is tthis the brand you use


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## a_c_arnold (Mar 7, 2008)

yep


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## trantran (Jul 6, 2008)

finally got everything together.
I did 5 coats of cement
3 coats of drylok
feels hard like a rock!

so far im happy with it but I think it looks a lil too dark, should it lighten it up a lil bit?

heres the 2nd coat
















final coat


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## cholile (Oct 28, 2007)

looks fantastic!


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## trantran (Jul 6, 2008)

UPDATE: 
ok so I got the tank up an runnig for 2 days, I notice theres some bubles on the background. why is this? I let it dry for 5 days before adding any water. I did 3 coats to make sure it was 100% sealed. 
help what should I do!? should I just leave it? will the bubble get any bigger?
should I take it out and reseal it? 
sigh..I spent 2 weeks doing this


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## a_c_arnold (Mar 7, 2008)

Your finish should be pretty solid. We're the bubbles their before you put water in the tank or did they form afterwards. I wouldn't worry too much about them because they are likely air pockets. Now would be the time to fix them, if they visually bother you. Once fish go in, it is much more of a pain. You could drain the water down scratch the bubble off and just drylok over top of the blemishes. If it were me, I'd probable just leave it as is. You will likely have rocks on the bottom that cover the lower area of the background anyway.


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## EricG (Feb 13, 2004)

I'll bet you're the only one that sees the bubbles. Happens every time I do a project too!! Rocks aren't perfect in nature either. Looks really good.

Eric


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## trantran (Jul 6, 2008)

their wasnt any bubbles when i put it in...heres a pics of it before









the one thing im worried is it might get bigger over time. i dont know if its air bubble or water got into it.


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## trantran (Jul 6, 2008)

EricG said:


> I'll bet you're the only one that sees the bubbles. Happens every time I do a project too!! Rocks aren't perfect in nature either. Looks really good.
> 
> Eric


did you also use drylok?


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## EricG (Feb 13, 2004)

I did. Actually a_c_arnold helped me do it. He's my wife's cousin. Never would have been able to do it myself.


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## chevyjock (Jul 16, 2008)

thats beautiful. i think i will look great and the dark will really pop out the colors of whatever fish you keep aswell as cast great shadows from your lighting.

im in the middle of doing one for my corner tank at the moment and will be putting up a how to soon, but mine has caves along the lines of a-c arnold


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## chevyjock (Jul 16, 2008)

i think it looks grat and the dark shade willl pop out the coloring of whatever fish you decide to keep.


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