Removed my sandbed

[liquid]

What do you guys think about epoxy on the silicone joints?

Won't stick to the silicone.

The one that I saw that cracked seems to have done so due to a rapid temp change in the glass.

Depending on the epoxy system, a failure due to the polymerization exotherm could definitely be a possibility. If it were due to the exotherm, I would hypothesize that a tempered bottom would fare better than non-tempered. It could very well be a combination of both stress fracture and temperature.

In Galleon's case, the bottom was tempered IIRC.

Shane

 

[polcat]

Hello Everyone,

I have spent far too much time at work today searching the literature and finding information on phosphorus regeneration in sediments. All I can say is that I am very humbled by the amount of information that is available in the scientific literature on this topic.

I thought that many of you might want access to these articles, so I have made them available in pdf form at the following link:

http://mit.edu/qhorn/Public/Reef%20Aqua ... 0articles/

Obviously I have not read these through these articles in their completion. I simply have not had the time to read more than the abstracts. Some may apply to reef tanks, some may not. I should also add that I found many articles whose titles and abstracts were very applicable to this discussion, but I was not able to obtain electronic versions of the articles. That means that I will need to physically go to the library and copy the articles the old fashioned way.

I encourage all of you who are interested in this topic to at least open these documents and read through the abstracts.

Homework assignment has been given. Hope I didn't spoil your weekend!

Kindest regards,
Quinn

And don't forget this one...http://www.terrapub.co.jp/journals/JO/pdf/5503/55030463.pdf

and this is fun reading...[/url]http://www.reefcentral.com/forums/showthread.php?s=&threadid=263482

 

[polcat]

oopps http://www.reefcentral.com/forums/showthread.php?s=&threadid=263482

 

[Anonymous]

Hello Everyone,

Sorry for my delay on getting back to you guys. Work is getting pretty busy so I haven't had much opportunity to pursue this topic.

No problem, we ain't going nowhere!

As promised, I posted a request on Dr. Ron's forum over on RC. You can read his response at:

http://reefcentral.com/forums/showthrea ... did=548275

Ron provided numerous references and some explaination for why DSB's are different from the sediments that most publications are based on. I have to admit that I have not had time to get to the library and read these references yet.

Well, this should stir the pot a bit. :wink:

Kindest regards,
Quinn

I think it is telling that he says that marine aquaria sediments do not have a high phosphate level while at the same time saying that testing for phosphate is nearly impossible and that no one has actually done any study on aquarium sands.

The publications he posted are all about phosphate in the 'wild', nothing about DSB's - and, like I said above, he says there are no studies on DSB's.

He cites his 'heavy metal toxicity' article as support for the exportation of phosphate in a reef tank, but the article only has one tangential mention of phosphate.

In other words, there is no scientific evidence to support his claims about DSB's. It all came from him.

It is nice that he is now saying that phosphate is limiting. It it odd that he hasn't realized that the phosphate being taken up by various organisms is what people are saying the problem is.

Thanks! :mrgreen:

 

[polcat]

Eco aqualizer...now that's funny :lol:

 

[DK]

"if an epoxy formulation shrinks only 1% upon cure, on a 6' tank bottom that will cause a net shrinkage of almost 3/4" down the length of a tank bottom. That's a fairly large stress IMO. "

Hell yes. If that is the basis, then it would be worth it to bite the bullet and go starboard or equivalent. Has anyone come up with an irregular surface that could be epoxied with sand and therefore have a better sand look?

 

[polcat]

Could you use two part expanding foam and epoxy it with the sand added. I was thinking maybe line the inside of the tank with plasic, shoot in the foam, then pull it out. It would be a good fit. Thinking out loud here, problem is foam would try to float..... :roll:

 

[Anonymous]

"if an epoxy formulation shrinks only 1% upon cure, on a 6' tank bottom that will cause a net shrinkage of almost 3/4" down the length of a tank bottom. That's a fairly large stress IMO. "

Hell yes. If that is the basis, then it would be worth it to bite the bullet and go starboard or equivalent. Has anyone come up with an irregular surface that could be epoxied with sand and therefore have a better sand look?

You could also cast the bed outside the tank. That way you can do it in sections if you have perimeter bracing or center bracing, and its removable.

Some people have cast FSB's with egg crate.

 

[Anonymous]

Eco aqualizer...now that's funny :lol:

Thanks! I removed it though because I thought it was a little rude.

 

[liquid]

Could you use two part expanding foam and epoxy it with the sand added.

Only if the urethane foam was UV stable (which they're not unless they've been formulated with light stabilizers).... I've seen a lot of people messing with urethane foams and I personally think they're going to run into issues with it in 2-3 yrs due to UV degradation to some degree. Hopefully not as long as it's covered w/ coralline...

You could also cast the bed outside the tank.

That would probably be the best way to do it as long as the surface is perfectly level that you're casting from. The big question would be what the water absorption percent the resulting cast bottom would have. You don't want it swelling, which is why people have been using UHMW (i.e. Starboard (tm)).

Shane

 

[Anonymous]

That would probably be the best way to do it as long as the surface is perfectly level that you're casting from. The big question would be what the water absorption percent the resulting cast bottom would have. You don't want it swelling, which is why people have been using UHMW (i.e. Starboard (tm)).

Shane

FWIU, the envirotex is not supposed to swell. If it did, it would be a problem for those who cast the FSB directly in the tank.

 

[DK]

To what degrre would cement/sandmix expand and is that what some have used in this context (over egg crate)?

 

[liquid]

To what degrre would cement/sandmix expand

Cement/sand shouldn't expand significanly. The bigger issue here is the high pH of a slab of freshly cured cement -- somewhere around 9-10 IIRC. You'd need to soak it in water with regular water changes until the pH stabilized out. IIRC there are neutral pH cements, but you pay a premium for them.

Shane

 

[Anonymous]

There is a big FSB thread on RC.
People who have cast epoxy directly in a tank generally let it cure for 4 days, then let it soak for a day and then rinse it again.

 

[Unarce]

I believe Thorite cement mix is aquarium safe and has no effect on PH.

 

[Anonymous]

Hey, I've been siphoning out my sandbed over the last month. Mostly I just want to increase flow beyond what will stir up the bed, and my big sump was a low flow area with about 6 inches of sand- I figured it must be settling too much stuff.

Surprising, most of the sand I have pulled out has looked pretty nice and clean; the tank is 2.5 years old.

Pardon me if this has been mentioned; I just read the 1st 2 pages and have to run. The reason Dr Ron always said that infauna (worms etc) was required for DSBs is he said that was the only device for diffusion of water through the sand. He said without the critters it would take 40,000 (or some similar crazy number) years for water to diffuse through 2 inches of sand. I heard that from him at the MACNA in Baltimore. I don't know why he never considered differences in salinity, tempertaure, external flow pressure, and other gradients to be issues. :lol:

 

[DK]

So, you could create the bed with Thorite with an egg crate base, make it wavy, do it in sections, then epoxy sand to the surface...........I might consider that on my 220 since it will be an SPS tank

 

[liquid]

then epoxy sand to the surface

Why go to this extra effort? Why not just cast the cement and press the sand into the wet cement?

shane

 

[polcat]

Maybe we should start a faux sand bed thread since there is lot's of good info here and the original thread was more about sand bed mechanics not asthetics? Ok, I'll start it.....

 

[Anonymous]

Hey Rich (or any others who might chime in)

Can you simply suck the stuff out with a large siphon hose with fish in the tank? Or are you likely to let loose some nasties and kill the fish? I want to remove most of the sand of my 50 since it's having a big cyano problem (and its plumbed into my 135 which does NOT have this issue) and I think its the sand having too many nutrients in it from another reefer's tank *couANDYgh*, although I'm not quite sure.

I would like to remove most all the sand (although skim off some since I do have quite the abundance of pods & mysid), and then leave myself with a shallower sandbed and I'm wondering the easiest way to go about this (dreading having to remove the fish, luckily only 3, and everything else).