plexiglass

[kgbenson]

Thanks Keith, I'm using silicone sealant made by GE which is supposed to be used only with plastic sheets. I hope this works, I'll keep u all posted.

No worries. But you may have the reverse problem - getting it to stick to the glass long term. My biggest concern is that the water will flood the substrate when there are crabs down there and unable to move upwards.

KEith

[kgbenson]

Ok so where would I go to find glass to use? Thanks.

Any glass store will cut glass to spec for relatively little cost, in fact, it may be cheaper than plexi depending on what product you were using. Make sure the smooth the edges cut glass can be insanely sharp.

Keith

[kgbenson]

My pools are built in and i love them. i have a filter in each and i treat them as i would a small aquarium. Regular water changes, and i use a syphon type aquarium cleaner to clean the substrate and crap that ends up in the bottom of the water. They have been together for a year now and holding well. I have had problem with water on the salt side, but i'm pretty sure it's a result of crabs coming out of the water and dumping their shell water. i'll be emptying soon and resealing to make sure. i used the GE stuff too.

Is the salt water becoming more dilute? Depending on the size of the crabs that would take a fair amount of shell water dumping I would think.

How do you compensate for evaporation of water and subsequent increases in salinity?

The silicone, if added in large amounts will hold for a while just based on friction, but for a nice looking seal that lasts a long time, aquarium folks consider it best to use glass with glass and a silicone bead and acrylic to acrylic bonded with weldon.

Keith

[kgbenson]

I'm also building for easy maintenance. My ponds are all plexi. Lift out for easy cleaning. i wouldn't recommend permanent ponds sealed in your tat.

Now this is a great idea, if they can be moved they can be more thoroughly cleaned.

Something like this would likely be fairly cheap to make if you have the acrylic skills, or a plastics shop can whip up a pair in no time flat for a reasonable price.

Personally I would like to see something like this: http://www.exo-terra.com/en/products/turtle_cliff.php

BUt sitting in a natural rock like basin

But with this as a Filter: http://www.tetra-fish.com/sites/tetrafi ... 76&cid=565

And a build in water fall.

I think some of the waterfall ideas are neat - but wish the basin at the bottom was much larger to accommodate larger crabs.

Keith

[kgbenson]

From this thread, I found this post:

It can be used, but you will need such quantities that it is less than cosmetic, and even then it will not have the safety of a true glass-glass silicone joint or an acrylic-acrylic bond.

I think the idea of removable pools made from bonded acrylic is a smashing idea - no one says you have to move them, but if you ever needed to change tanks, you could keep them.

Keith

[tojo]

Now this is a great idea, if they can be moved they can be more thoroughly cleaned.

Something like this would likely be fairly cheap to make if you have the acrylic skills, or a plastics shop can whip up a pair in no time flat for a reasonable price.

Personally I would like to see something like this: http://www.exo-terra.com/en/products/turtle_cliff.php

BUt sitting in a natural rock like basin

But with this as a Filter: http://www.tetra-fish.com/sites/tetrafi ... 76&cid=565

And a build in water fall.

I think some of the waterfall ideas are neat - but wish the basin at the bottom was much larger to accommodate larger crabs.

Keith

Thanks Keith, those are some of the stuff I'm looking for. What is your background, you seem to have some experience with glass work and whatnot?

[kgbenson]

Thanks Keith, those are some of the stuff I'm looking for. What is your background, you seem to have some experience with glass work and whatnot?

I have actually done a limited amount, but I am very interested in aquaria and work in a facility with a public aquarium and decisions such as water quality, sealants, solvents can occasionally filter over into my area.

I am very interested in setting up something that sees to the crabs needs, but also has a certain level of automation, mainly for their protection as they seem to appreciate a certain level of consistancy.

Keith

[kgbenson]

There is a material by Dow Corning, product number 1250 that will alter the molecular structure of the plexi such that it will bond to the silicone, otherwise I would question the long term nature of a glass-silicone-plexi bond. In fact, I just got that information from a senior aquarist who would never count on such a bond to be anything other than very temporary, and prefers to work glass-glass, plexi-plexi unless forced to do otherwise and then he uses the aforementioned Dow product.

Other than that, just think about it, crab on the bottom, halfway through a molt, sudden influx of water (salt or otherwise). Not good, and with a slow leak one might not notice it until much later.

Be safe out there.

Keith

[Kilimanjaro]

If anyone gets a quote on how much glass cutting at Lowes or Home Depot costs, I'd really appreciate it.

I was looking online and found one site in which the two pieces I needed would be $18 each. Not too bad, but shipping for 7-day was $24... I'd much rather take a drive to Lowes or Home Depot.

I figure for a standard 55 gallon tank, I would need two pieces:

1 longer than the other to span the width of the tank, a little less than 13".

Then, I'd need one that's shorter that would connect the longer piece to the side of the tank, which would be around 6" for a decent size pool.

Both would be around 6" - 7" tall, a little higher than the substrate.

That way, it would work like this (the dots are just place markers):
_____________
|................|__|
|_________|__| Obviously, the long one spanning the width is one piece, and the piece dividing is to divide salt/fresh. I think I would use these filters:

Hagen Elite Mini

They're used for 3 gallon aquariums or lower, which is ideally what I would need for my two small pools. the only thing I would worry about is Eco-Earth clogging up the filter. Anyone have an idea how to prevent that?

I am probably going to have some decoration for them to be able to get into and out of the pool (maybe some type of coral decoration for the saltwater side and some type of log for the fresh) and then I think I'm going to choose a coral-sand substrate mixed with some river rocks and brown gravel.

Sounds like a good idea? I really appreciated your opinion, KG. I would have been in trouble if it weren't for your memo about the acrylic/glass bond not being strong!

[kgbenson]

If anyone gets a quote on how much glass cutting at Lowes or Home Depot costs, I'd really appreciate it.

Hit a local glass shop, tell them what you are doing and they can a) cut the class to spec, B) bevel and polish the edges, and C) possible put a diagonal cut at the corners so as to not interfere with the already present silicone beading.

Also - hit some of the aquarium websites for silicone tricks (like using painters tape to avoid leaving excess silicone behind) - those reef guys are often DIY wizards.

Keith

[Disgruntled Crab]

I am also doing a drop in pools for my new 30 gal tank. As long as i use 100% silicone for plexi glass i should be good to go and be safe for the hermies right?
Cause if aquarium silicone is really made for glass it wont hold up compared to a silicone for plexi?

[Scary Clam]

First of all, I also want to clarify that maybe it's just me; I hear other people have had success with it.

After I read this thread, my personal thoughts were well kgbenson is probably right, but how can all these other people have made pools with this stuff and not failed and I can't find this stuff anywhere. So I tried aquarium silicone and it didn't work. So that's when I ordered acrylic cement from Ebay; I will not take a gamble if I have molters down.

Aquarium silicone claims to be 100% silicone, so does the caulking stuff and the stuff near the plexi (that says it's for plexi) at your local big-box hardware store. I don't see the difference if they're all 100%. In making my pools, my attempts to use aquarium silicone failed 3 times. When I'd repair a leak, a new one would form elsewhere. I just didn't trust it even when I finally got it leak proof. I didn't even need a razor to finally remove it either, I pulled it off by hand. If I can do it that easily, I know my crabs will be pulling it apart too.

On the other hand, maybe the stuff from the hardware store is somehow better. Maybe there's a .5% additive in the many varieties of 100% (99.5% rounded up) that makes for tons of repackaged 100% silicone products that make them some how better for acrylic. If they do, are they tried and tested crab safe additives? Especially if the manufacturer expects you to be caulking a window with it. In addition to the recommendation on here from kgbenson- I can back up the claim by people who build custom acrylic aquariums, from many other aquarium sites. Maybe I put too much thought into this, but like I said, I won't take a gamble with a leak when I might have a molter down.

[Disgruntled Crab]

Hmm know i am confused on what to use

[Guest]

you could use a large sealed shower caddy.

[Scary Clam]

Hmm know i am confused on what to use

Sorry, I always write too much! I didn't mean to confuse! If I had to choose again, these would be what I'd be choosing between:

-Custom cut glass with aquarium sealant
-Plexiglass (acrylic) with acrylic cement

Hopefully someone else will chime in and plead the other side of this (success with plexi and silicone). As I said, it might just be me! ;)