Rimless glass build help

[jsjonesrdh]

You say that a smaller tank isn't really a candidate for use of spacers, why is that? If new silicone bonds well with partially cured silicone, it would be quite helpful for me to be able to use spacers, clamp everything and then pull them. I could inject silicone into the spacer area. I only wonder if this is a viable option because free handing my panel space seems to be difficult at best and a screwup means complete dismantle.

 

[uncleof6]

No it would not. Don't use a crutch, it is not needed, and they are only used on heavy panels, the weight of which--would squeeze the silicone out. You lay a bead down, you cannot inject anything anywhere after the bead is laid down. Big air bubble. It is not really a viable option.

You probably can't get the spacing right, because you are not using enough silicone, and you are using the clamps to set the seam width. At your stage in learning, you want a LOT of silicone to clean up. On a tank scolley's size (75 gal. I can link to the article if you want,) if you used a tube per panel, you have not really used too much. The panels are set by hand, thus the seam width is set by hand. The clamps merely hold the assembly motionless, during curing. Account for a little compression, when setting the panel by hand, for the clamps.

Yes, a screw up means dismantle and start over, after hours of cleaning silicone residue off the glass. That's the drill.

The hardest part is getting the seam width right. You can't learn it using a crutch. Honestly, just as I tell everyone wanting to build a tank: you would be better off money wise and time wise, to buy a tank, or have it built for you.

 

[jsjonesrdh]

Ok, ill give it a shot sans spacers. Also, I am building the bottom panel inside of the sides for strength ( tensile vs. shear) so I'm not worried about glass weight squeezing out silicone.

Really, I have never let a learning curve keep me from attempting to learn a new skill. I find it enjoyable and the sense of accomplishment it something I love. Like I said before, I knew that I could screw up and have to start over...although it would be nice to keep them to a minimum.

You are right on with your call on not using enough silicone. I will definitely be laying a larger bead next round. I just got done removing all of the silicone and my hand is on fire Scolley, I feel for you, 6times on a 75 gallon !... I would need some healing time between attempts.

You mentioned euro bracing for the tank and I thought about it for the bottom panel but I hadn't planned since I have seen rimless tanks this size built without them. Would you recommend I use them?

 

[uncleof6]

If the bottom panel is not thicker than the sides, then yes, it is pretty much obligatory.

You are correct on the tensile vs. shear, with sides around bottom. According to Newton's Laws of Motion, the shear at the seam (downward force of water, ambient pressure, acceleration due to gravity, etc.) is negated by the equal and opposing upward force applied to the bottom panel, by the stand.

Actually though, technically, that is not accurate. The bottom panel will deflect down, the stand will deflect down, the floor will deflect down, so forth until the upward force is equal to the downward force. But it is close enough.

 

[uncleof6]

editing of previous post interrupted by back up......

If the bottom panel is not thicker than the sides, then yes, it is pretty much obligatory.

You are correct on the tensile vs. shear. However, with sides around bottom, according to Newton's Laws of Motion, the shear at the seam (downward force of water, ambient pressure, acceleration due to gravity, etc.) is negated by the equal and opposing upward force applied to the bottom panel, by the stand.

Actually though, technically, that is not accurate. The bottom panel will deflect down, the stand will deflect down, the floor will deflect down, so forth until the upward force is equal to the downward force. But it is close enough.

The force pushing the front, back, and side panels away from the bottom panel, (and each other) has no significant opposing force, (ambient air pressure is all,) so a very wide seam around the bottom is needed to hold the tank together. Why? The force (pressure) is greatest at the bottom, and the tensile strength of silicone is not what holds the tank together. It is the adhesive strength, that holds the tank together, and that is the weakest property of silicone. The adhesive bond between the silicone and glass, raises the magnitude of force required to overcome inertia. (tendency of an object to remain motionless.) The wider the seam, the "stronger" the seam is.

That is for the seams. The further you get from the seams, the lower the magnitude of force required to get the panel moving. This brings us to glass thickness and safety factor.......

 

[jsjonesrdh]

Got it. I did a bit more reading of material physics and I have a few of my own misconceptions clarified. The tensile strength has nothing to do with the glass, that is in reference to the material alone. The specs for adhesive strength for the momentive rtv data sheet are not listed probably because there are too many variable that would affect the bond ( as well as specific material choices) The tensile strength is rated at 400 lbs per squared inch. Any ballpark idea of what adhesive strength is to glass is?

In regards to euro bracing the bottom, I have looked though several pics for builders and the longer brace in the front and back runs into the side panels and the shorter brace sits in between. Any specific width I should have them cut to? It seems 2-3 inches should be sufficient since I'm mainly trying to increase surface area for the front/back/side panels to bond to which is determined by the glass thickness.

 

[uncleof6]

Got it. I did a bit more reading of material physics and I have a few of my own misconceptions clarified. The tensile strength has nothing to do with the glass, that is in reference to the material alone. The specs for adhesive strength for the momentive rtv data sheet are not listed probably because there are too many variable that would affect the bond ( as well as specific material choices) The tensile strength is rated at 400 lbs per squared inch. Any ballpark idea of what adhesive strength is to glass is?

The peel strength, which is sort of a pointer, of RTV-100 series IIRC, is 40 lbs/in. As the silicone cures (over 1 - 2 weeks) additional cross-linking occurs. Ultimately, after completely curing, "adhesive strength of the bond will exceed the cohesive strength of the silicone rubber adhesive sealant itself." From Momentive literature. A contradiction, I have not bothered to resolve.

In regards to euro bracing the bottom, I have looked though several pics for builders and the longer brace in the front and back runs into the side panels and the shorter brace sits in between. Any specific width I should have them cut to? It seems 2-3 inches should be sufficient since I'm mainly trying to increase surface area for the front/back/side panels to bond to which is determined by the glass thickness.

Depends on the size of the tank, but 3 - 4" would be an average. Be aware, that silicone away from the edges of the euro (securing to bottom) will not cure, so be careful with the application.

 

[jsjonesrdh]

I thought about the silicone not being able to cure due to the seam width and lack of air exposure. I had planned of putting silicone on the edges that will contact the sides of the aquarium (obviously), where the braces butt together and one bead in the inner edge that faces the inside bottom of the aquarium. Silicone anywhere else on the brace would violate the recommended 1/4" cure depth max.

 

[jsjonesrdh]

Ok an update!

My second attempt after a several week recess. I laid out all of my panels on a sheet of MDF and marked the location of all the panels of glass including the spacing. This made my alignment much easier and precise.

I use a substantially thicker bead of rtv and I have 0 bubbles The silicone is currently curing and I will leak test in a week. I will have some pics up this weekend.

Uncle, when you say lower Euro-bracing is mandatory with rimless aquariums, does this apply to all sizes? I'm not against doing it, I was wondering if there mathematical reasons for small tanks. I will admit that I only have slight reservation due to the possibility of screwing it up and having to cut everything apart again? Do you have a pic that shows proper silicone placement for bottom bracing?

 

[Reef Developer]

Im planning on doing a 10 gal rimless and want to know the euro bracing answer too. Even though I havent seen a small tank with euro bracing.

Jsjones or anyone else, what do you do with the silicone that oozes out on the outside? Clean it with a razor and acetone right away, or make a clean cut with razor when it drys (assuming the glass face has been taped off).

 

[uncleof6]

These type threads have a tendency to turn into tank building classes. I have no intention of teaching tank building. My only mission is to keep folks out of serious trouble.

In most cases, you are time, money, and risk factor ahead, to have the tank built for you. Or buy a manufactured tank, of similar dimensions. There are too many variables. The only way to learn it, is to do it, preferably with hands on guidance by someone who has built more than just a couple tanks. In other words: apprenticeship.

Lacking the availability of professional assistance, build small tanks for practice, and don't expect them to hold together. I would strongly urge you not to build a DT you are planning for you reef, as a first project, honestly not as a third project either. When you can write your own set of instructions, based on success, you are ready.

Cut it with a razor blade later on. If you did your taping well, you won't need acetone, or any chemical.

 

[jsjonesrdh]

As uncle said, I let it cure for several days and the cut the excess flush with a fresh blade. Smooth lines

 

[jsjonesrdh]

Just an update, going on day 7 of my water test and everything is looking good. I have not installed my custom glass overflow yet since I wanted to make sure the tank would hold water first. Ill post some pics later tonight.

I think one of the tricky parts was how to lay out the silicone for the lower euro bracing. I used 1/4" glass for two braces that ran the length of the tank. I would have liked to use 3/8 but since the silicone pressed against the bottom of the tank may not have fully cured since momentive recommends a max cure depth of 1/4". I have use about 2 full tubes of silicone for this build.

 

[jsjonesrdh]

Ok so time for the good stuff! Pictures!!

The tank was built on the stand. I leveled it, XPS foam, wax paper.

Glass was cleaned, taped, cleaned again with acetone, denatured alcohol and then wiped with a clean lint free cloth.

And the trouble starts, as i posted before, i tried to put the tank together too fast and my seams were inconsistent in spacing and i had a large air bubble on the lower front panel. I slid it into place improperly and i did not use enough silicone.

Sloppy seam with 1/8" gap instead of closer to 1/16"

So after waiting for the silicone to cure, i begain the PAINSTAKING process of cutting it all apart and cleaning it. UGH.

 

[jsjonesrdh]

After my hand fell off, i prepped everything again. After uncles recommendation to slow down, this attempt went much better. I added an MDF jig with all the edges including seam width marked on the jig so i knew exactly where every piece should end up after proper placement. I modified some plastic right angles that i had on hand after making sure they were true by checking them up against a much more accurate precision square.

Parallel clamps were but in place to ensure there was consistent widths between the panels. I used much more silicone this time and was able to produce bubble free seams. The silicone was allowed to cure for a week and then trimmed flush

I then re-taped the seams for the inner fillet. There were a few micro bubbles under the fillet but im not worried as there are there to protect the structural silicone. I then added two 3" wide 1/4" glass braces along the front and rear for added strength. I chose 1/4" due to the maximum cure depth of the silicone. Any deeper and it may not have fully cured.


After waiting another week, i water tested for several days to check for leaks. None were found.

Success so far. It was then time to build the glass overflow. When i orderd the glass for the overflow, i did not know it was textured but after placing in in the aquarium, i like it.

Dry fitting the overflow

 

[jsjonesrdh]

I prepped the surface for the overflow and siliconed it into place

Instillation detail

Another angle. I will be using 1/4" black silicone tubing for the open channel overflow since i do not like the look of the white fittings.

I am using barbed fittings to save space behind the aquarium and allow cleaning of elbows. I did not want to have any black caps protruding above the back of the aquarium

Egg crate was cut and installed to keep rock off of the glass

Aquascaping with pukani rock. I used fiberglass rods drilled into the rock to hold it together. The structure on the left has a lower stabilizing rod that will be covered when the sand goes in.

The final silicone detail was cleaned up with a surgical blade after i took this picture.

The XPS foam edges under the tank were painted black. Who wants a hideous purple mat under the tank?

Rear pic

Ill have more pics later. I sure hope this doesn't spring any leaks but i have been happy with the way everything is looking so far.

 

[Reef Developer]

Hey, nice quality clamps you have there! Good idea with the plastic squares, for anyone who didn't notice jsjones just nibbed (cut) the corners so the silicone had room in the corners.

Well done, looks nice all around. I can't remember what you said earlier, but did you use the RTV Momentiv silicone or something else? I did on my build and **this stuff is tough**. I measured my tank while empty and while full and there was no varience, meaning the silicone didn't flex at all.

I like the egg crate idea, but wonder if it will interfere with micro's from doing their job. Will there be any problems with creating a bunch of little boxes holding what will be livesand?

 

[jsjonesrdh]

I did use the momentive rtv silicone. I had only about 1/32" of deflection when full. You are right about the modification of the corner squares. About those, I looked an some of the better built corner clamps and for the price, I could not justify them. I brought a woodpeckers precision square to the store to check the angles of some of the cheaper clamps and some were worse than others and still at 20$ each I wasn't along to spend 80$ on cheap clamps.

I had several of the plastic ones already so I trued them on my table saw and routed an extra slot to accept the extra spring clamp. After placing one side I was able to align the adjacent panel and clamp it.

As far as eggcrate and the sand, your concern crossed my mind. I will have about 3/4" of sand above the eggcrate so I'm not particularly worried. I stir the sand for cleaning with water changes anyway when I'm siphoning.

Thanks for the feedback.

Sent from my EVO using Tapatalk 2

 

[jsjonesrdh]

The tank is filled, sand is settling and the overflow is working flawlessly. I need to do some touch-ups on the aquascaping including concealing that last fiberglass rod. Finishing up my lighting is next on the list. Ill post some more pictures as i progress.

* that is not a bubble in the bottom seam...just a reflection

 

[rovster]

Looks great! Thanks for sharing your experience! Not sure if you answered this, but what did you spend on glass?