PVC risers for Live Rock with DSB

[Tankless in Dubai]

I had thought that by elevating the rock off of the sand or at least by diminishing the area in which the live rock sat directly on the sandbed would improve water circulation, and generally allow greater movement by the sand dwelling creatures, etc.

I had read about this somewhere, it may have been something associated with plenums, I don't recall. I also read Dr. Ron's DSB article that mentioned nopt to use PVC risers but I forget now what the reasoning was. I'll have to go back and take a look at that.

I was also hoping that the PVC might add some stability to the rock structure.

 

[Anonymous]

Dan,
My only reason for being involved in this thread is that many practices in this hobby are based on habit rather than science. Putting PVC risers is one activity that has no apparent value. Does it hurt anything? I am not sure, but when one of the origional advocates of the DSB says it might, leads me to believe the practice is useless. Apparently, PVC risers and or eggcrate reduces the ability of both microscopic animals and water to move through the sand. Setting the rock on top of the sand does not. Dr. Ron has been asked this question many times. If you go to his site and do a search on PVC or eggcrate, you can read what he has to say.
http://reefcentral.com/forums/forumdisp ... forumid=40

 

[Anonymous]

Well, if you read through the thread you will see a couple of reason that altho not earth shattering to have some value. I did the search at Dr Rons, and of the posts I read the only one in which he addressed the issue directly he said it was harmless. I don't consider Dr Ron to be the last word on husbandry anyway because he has a fair amount of illogical pedantry in his own discourse and furthermore doesn't have much of an aquarium.

 

[O P Ing]

hi.
Well, I went over there and did not really find much from Ron in the "FAQ" nor the post in the Ask Ron forum.

Apparently, PVC risers and or eggcrate reduces the ability of both microscopic animals and water to move through the sand. Setting the rock on top of the sand does not.

All I read is not much more than opinions and personal preference. Do you have a specific thread that you can help me understanding the logic behind your statement?

 

[cvye]

I don't consider Dr Ron to be the last word on husbandry anyway because he has a fair amount of illogical pedantry in his own discourse and furthermore doesn't have much of an aquarium.

You only get to be a guru in this hobby after you've stopped keeping a tank. And the longer it's been since you've kept one, the more respected you get. Otherwise, you're just a "hobbyist". :roll:

 

[Anonymous]

You guys are right. I don't think Dr. Ron is the only source of science in the reef community. But at least his opinions are based on science. You should look at his salt evaluation. It might open your eyes, if you aren't already blind.

 

[Anonymous]

Sorry, didn't mean to start an anti-ron thing :wink:

However, I've seen the article- and am sticking with IO so I just might be blind!

 

[O P Ing]

But at least his opinions are based on science.

hi.
Ron is an undisputed expert on a class of mullusk. However, not everything an expert say is all based on science. As always, the previous statements are just a general statement not meant to be directed at Ron in particular. I respect him, but just wish that he give more concrete reasonings for his advices.

 

[Anonymous]

Ok,
Dr. Ron's advice on how to set up and maintain a sandbed is ok! But when it comes to the super-technical evaluation of PVC risers, he is just not qualified.
How about someone here giving a reason PVC risers are a positive to a reef tank. Now remember, risers don't save live rock because you can set the rock on the sand. (Many do this besides that stupid Dr. Ron and it works.) Risers don't increase the area of sand bed. So what good are they?
You could ask Instant Ocean for advice, they certainly have a scientific grasp of their products don't you think?

 

[bradsark]

I had been having trouble getting my aquascaping to look how I wanted it. My tank is 30" high so it was difficult to slope the LR and have it look good and be stable. After reading this thread I cut pvc pipe into 10" pieces and 4" pieces. I put the 10" pieces in the back 1/3 of the tank and covered them with a layer of eggcrate. I then put the 4" pieces in the middle 1/3 of the tank with a layer of eggcrate. This level sits about even with the DSB. In the front 1/3 I pushed the LR down into the sand. I was finally able to arrange the LR how I wanted and have it be stable. So after much debate (with myself) I am glad I did it. I don't know if it is the absolute best technique or not (I guess everyone you ask has a different opinion) but it sure did make the tank look good.

 

[Anonymous]

How about someone here giving a reason PVC risers are a positive to a reef tank. Now remember, risers don't save live rock because you can set the rock on the sand. (Many do this besides that stupid Dr. Ron and it works.) Risers don't increase the area of sand bed. So what good are they?

Haven't we already given those reasons? If you have big rock sitting on top of the sand there clearly won't be much circulation over that sand, so I think increased circulation is a benefit. And they do save on live rock bacause just because other people set the rock on top of the sand, I wouldn't. You may have had a fine experience doing it that way but I wouldn't be comfortable with the stability of it, particulary if there are burrowing gobies etc involved. And also using pvc you can create somestructures that you wouldn't be able to do otherwise, like towers, overhangs etc.

If you don't want to use pvc thats just fine, I don't have it in my tank either. But nobody has produced anything negative about it so whats the big deal? The only thing I found on Rons site is that eggcrate buried in the sand would inhibit the lateral movement of organisms, but the guy in question wanted to put it on the bottom of a 5 or 6 inch sand bed. I really doubt it is going to be a significant issue there.

 

[Anonymous]

Dan,

.."so I think increased circulation is a benefit."

Well that is your opinion, but most of the circulation in the DSB is caused by the infauna and they do just fine under Live Rock. Live Rock sits very well on a DSB based on the experience of many. If you "choose" to use PVC thats fine. But the reasons given all just opinions without basis.
So the next time this type of thread comes up and people say PVC risers are great because they save live rock or improve DSB performance, they will still be giving bad advice.
Why not just say you like the idea and not try to defend it with opinions. I like a blue background on my tanks. It improves DSB performance and Light Intensity. Everybody should install one.

 

[JohnRogan]

I like a blue background on my tanks. It improves DSB performance and Light Intensity

I did not know that blue also has benefits. I did buy a black background on my because of the benefits associated with the pH level.

 

[Anonymous]

So the next time this type of thread comes up and people say PVC risers are great because they save live rock or improve DSB performance, they will still be giving bad advice.

Thats your opinion. I disagree.

 

[fishfarmer]

How about someone here giving a reason PVC risers are a positive to a reef tank.

Too keep my 20 lb coral head from crashing into the side of my tank or from crushing my fish.

 

[O P Ing]

I did buy a black background on my because of the benefits associated with the pH level.

hi.
Hmmm... how does the color of the background affect the pH level of the water????

I feel that it is a bit unfair to bring Ron into our discussion too often because he does not frequent this board very often. Second, many thing we said are our interpretation of what we read in his forum, and not his opinion. For example, Ron don't have a strong objection to the use of PVC setup (Mime in public park, etc.), but I might depict him otherwise in my posts.

Anyway, let me continue on. Keep in mind that there are a million ways to setup your tank, and there is no single "correct" way.

Risers don't increase the area of sand bed. So what good are they?

Well, they do increase the area. If the sand bed is 4 inch thick, but have of the volume is occupied by LR that embedded in the sand, then the actual volume of LS is only the remaining space. The direct relation between volume and surface area means that a 4 inch sand bed without LR will have more surface area than one with LR. (LR also have surface area, but compare to sand, the surface to volume ratio is much smaller.) Now, with the use of PVC, you keep most of the rock out of the sand, so the use of PVC riser does incrrease the area of sand bed.

I agree (FWIW) somewhat with Ron on the benefit of sand/rock interface. There are some critters that prefers to broswe around the rock, so it is a good idea not to separate the rock from the sand thru out the tank. As I said, in the tank I am setting up, I have two layers of rock, one layer on top of the rack, while another layer is right on top of the sand.

 

[Ben1]

In my 20h seahorse/softie tank I used a 3/4" PVC pipe going diagonal across the tank. I drilled hole in the pipe and in my live rock. Then secured the live rock along the pipe using cable ties. This way it gives me an easy way to stack high without needing a huge base and makes a great overhang reef. Only one contact point on the sandbed to prevent and dead spots. IMO this makes a big difference. In a slow flow tank detritus builds up in dead spots fast and can be problematic. I need the slow flow for the horses.

In my 75 SPS I use many powerheads and like a lower open stack of live rock right on the sandbed giving my more area for growth and nice caves stacking the rock openly. Both ways work, no advice is bad advice.

 

[Anonymous]

Well then I have to agree. I will install PVC risers to improve my DSB performance. That along with the Blue Background will make my tank one of the very best. Get out the sunglasses.

 

[ENS]

I created a shelf riser system for my LR in order to allow much increased circulation and no dead spots at all (plus less live rock needed) -- it has worked very well for me.

Basically, I took a sheet of clear acrylic, about 2/3 the length of my tank and about 1/3 the depth (and cut it into 2 pieces to be able to easily get it into the tank) and drilled lots of holes in it ranging from 1" to 3 1/2" diameters -- basically making a large swiss cheese look to allow complete flow through it and fish to swim above and below. Than I took 1 1/2" diameter clear acrylic tubes of 7" and mounted four of them under each of the two sheets of acrylic (also made large holes in the tubes of opposite sides for flow-through. This is more stable, in my opinion, than pieces of pvc or egg create - very sturdy to stack LR on.

These are in my tank covered in LR and has LR in front and around the sides of the shelves (w/ lots of openings for fish and water circulation)hiding the shelves, and it creates a fully open area under the LR of about 3 1/2" above my DSB (actually some small pieces of LR rubble under this for creatures to use. You cannot tell they are even in the tank without really really looking through holes in between pieces of LR that surround it. I also have a small submersible pump under the shelf which insures that the water flows under it -- I have no dead spots and if something dies or need to be retreived from under LR, I simply move a couple pieces that sit on the sand that cover the front of the shelves and reach in the remove the item.

It has worked well for me.

 

[Anonymous]

ENS, I would love to see a pic of that!

Louey