Silicon for tank

[johnnytanki]

Hi,

I have a 4ft planted tank. It come with 3 supported glass on the top where you normally placed the lights. 1 glass on each end and the middle is another peice. Few nights ago, i noticed the middle piece of the glass suddenly drop into the water. So wondering now how and what type of silicon should i use to glue back this piece of glass. Is it safe if i just leave the tank with the 2 pieces of glass at each end and then dont glue back the middle piece? Hope to hear some advises from all. Thanks

[evolim83]

Wat is the thickness of your tank?
8mm (unlikely) or 10mm (most probably) or 12mm (good to have, but expensive)?
How old is your tank?
There are 2 possible reasons that cause the center bracing to come off:
1. The tank manufacturer used poor silicon and after years, all starts to come apart!
2. The thickness of the glass of your tank is not strong enough to substain the pressure of about 400L of water . Therefore the width expanded, causing the center brace to come lose!

In both cause, I would suggest your silicon back the center bracing!
I used regular silicon that are found in DIY stores. However, try to go for those non-toxic ones.
I dun think those sold in LFS are strong enough for bracing!

[johnnytanki]

yup..mine is 10mm..wow if the thickness of the glass is not able to withstand the400L of water...then that will be very dangerous laio...thnk i better get some silicon....scrub off the old silicon and paste it back...but not any easy task lah...need to clean up that area first...make sure is dry and paste it back.
thanks for your advise !

[celticfish]

same thing happened to me too.

its easier to use a razor blade to scrape it off. you're right to make sure the area is clean and free of the old silicon.

make sure use empty you tank before applying the silicon. the bending can be quite large. i measured mine to be about 10mm empty vs full tank. (added info - tank size is 4' X 1.5' X 2')

make sure you cover the whole area avialable to maximise the bond. adding another liberal helping around the side helps too.

[Justikanz]

Err... Drop the water flow to about 50% and silicone back the middle bracing... When it is completely dry (~2-3 days), wait for as long as you can before you fill the water again to the desired level... Use the carpenter's tool for checking leveling to check for buldging... If buldging is bad, you might want to wait longer to up the water level or consider changing a new tank...

[johnnytanki]

wow...thanks for all the bro adivse.....hope that the bending is not that much..will measure when got time..thanks a lot again

[bossteck]

Hi,

I have a 4ft planted tank. It come with 3 supported glass on the top where you normally placed the lights. 1 glass on each end and the middle is another peice. Few nights ago, i noticed the middle piece of the glass suddenly drop into the water. So wondering now how and what type of silicon should i use to glue back this piece of glass. Is it safe if i just leave the tank with the 2 pieces of glass at each end and then dont glue back the middle piece? Hope to hear some advises from all. Thanks

Hi hi,

You will need to completely (I mean really completely) remove all the old silicon from the centre brace and the area on the tank where it used to be. Use a pen knife.

Then for added effectiveness, i suggest you use those alcohol swab (available in pharmacies) to clean the area where the centre brace will be siliconed back on. Do the same for the glass brace itself.

You might want to put some masking tape to mark the boundary of the silicon (so when it's finally cured, you just strip the masking tape and you will have a decent looking repair work)

Most silicon takes about 3 minutes to skin, 48 hours to cure but a much longer time (give it a week) to be fully cured where it will achieve maximum strength.

You can use the broad side of a cutter to smoothen the silicon befores it skins to give it a nice finish.

The most difficult part is perhaps finding a way to hold the brace in place while you apply silicon and while it cures. If you can afford the time/space/effort, i recommend you fully drain the tank, there's no need to remove the gravel, just cover it with some plastic sheet in case silicon drips onto it during your repair.

Since the brace will probably not be in contact with the water, what type of silicon you use probably doesn't matter. But to be safe, just make sure it is 100% silicon.

Good Luck!

P.S. How old is the tank? If the center brace can fall all of the sudden, how sure are you that the silicon on the sides won't give way suddenly?

[Justikanz]

The center bracing is at the most stress... Also sometimes, we can add stress to it by placing things on the bracing...

I had a 3ft tank that had the center bracing dropped off suddenly too... There seem to be a slight buldge at the tank center... Was really scared. Discarded the tank for a 4footer after siliconing back the center bracing for a few months...

[johnnytanki]

hi...wondering how can i glue it back if the expansion is around around 1-2mm..normally there is a small stripe of glass below this centre piece to support it....but due to the expansion.....the centre piece is not able to sit on these 2 stripe of glass on each side....wondering if i drain off the water to 50%...will the glass shrunk back so that i can glue back the centre piece...please help !!! thanks

Btw the tank is quite old liao..no idea how old is it as i bought it 2nd hand from someone......

Also i think is not possible to fully drain the water...as there are plant and livestock such as angel, tetra, yamato inside.... Sigh...what can i do ??

Yes you are right....i am not sure whether the other 2 end will drop out too....most importantly is scared tat the tank will give way !

[celticfish]

the centre is subject to the most stress.

look for bubbling on the silicon seals. if there are lots of bubbles i suggest you consider changing your tank. otherwise you can rebond the piece and carry on with this tank. mine is still okay after the rebonding.

draining 50% may help but if you can drain more - better. the top half applies the most stress. like a crowbar effect from the bottom.

[Justikanz]

Yes, since the expansion is actually quite a lot, suggest you drain the tank and temporarily house the animals and plants in a smaller tank or pail... Try to use something to support the tank front to try to 'pressure it back to shape'...

If financially allowed, I'll suggest you change a new tank... cos the process may take some time... My 2 cents...

Oh, btw, the tank won't suddenly give way... It usually springs a leak somewhere first... So, just be on the lookout... But the center bracing is at the highest stress and so it tends to give way first, anyway...

[johnnytanki]

Thanks.....i did not drain all the water cos no spare tank to house all the plants and livestocks.....oni drain it till 30%.....then start the work of glueing back...damned siong....after ard 3 hours...i top up the water till 50%...wil change water for 2-3 days at 50%......after that will top it up to full...thanks for all the help

[Justikanz]

Know it is a headache... But try to wait for longer before you fill up the tank... Else you may have to repeat the whole process... Good luck!