rubble rock and grunge rock

[MikeS]

Hey Mike

I'm looking at using some live rock rubble as a substrate for my new tank...I saw you have grunge and rubble on your site. I plan on crushing the rock down to 4-6mm. Anyway, I was wondering if you had an idea of the volume of rubble or grunge per pound...I'm going to need around 2 cubic feet of it, trying to figure out how many pounds that will roughly work out to be.....

MikeS

[badnemo]

I have a question on that to ..... MikeS .... do you think if I bought some grunge do you think it would place the tank into another cycle? I have a 15 gallon nano tank. I was thinking on placing the LR in the my new CPR backpack II protein skimmer rather then the bio balls .... what you think? Maybe a couple peices from the LR that look nice in the tank. Or should I run plant life in the protein skimmer?

[MikeS]

Hmmm...I'd avoid both bioballs and rubble rock in the BakPak skimmer...these will simply increase nitrate levels...I'd just leave the biochamber in the skimmer bare...

Mike

[mdmaquatic]

Hmmm, i'm not sure on the volume versus poundage. I really haven't gotten that far. The "grunge" is mostly mud settlement and liver rock fines. I know alot of guys like to use it in a refugium for copes and other critters to multiply in. The rubble is all different sizes from 3" or so down to about 1/2"-3/4" in size. Nice for frag mouting.

[MikeS]

the rubble is likely what I'd be interested in...I plan on smashing it down to around 3-6"mm for use in a plenum substrate

Mike

[gman0526]

Mike talk to me what are you scheming bro?

[MikeS]

When I move the contents of the 55 to a 75 this spring/summer...I'm going to do a Jaubert style plenum with 4 inches of a coarse substrate on top...(hence the 3-6mm crushed live rock)...what more perfect media for a substrate? :-D

[bigfoot]

there is gotta be a better way mike.... i think if you used crushed lr then you should just use some kind of argonite gravel im sure its available and you dont have to smash it up i had a friend who put crushed coral in a tub in his porch added salt water and a bout 7 tiger shrimp to it and a bunch of little live rocks he had let it cure till all was cool about 1 month and then he put it in his display tank and he liked the results plus id be pretty easy i would think to seal off the bottom in spots where coralline spread across the bottom of the tank?

[bigfoot]

plus sand looks prettier you could use some kind of fine grade lava rock?

[mdmaquatic]

Why a plenum type system mike?? I thought everyone left those behind?? To me they are nothing but nitrate traps.

[MikeS]

Bigfoot...
CC would be the correct grade, but the problem with CC is phosphate saturation and lack of porousity. Sand will be too fine of a media for the plenum to function properly long term, you will be reliant on bugs and such for diffusion. Phospahtes are also an issue with aragonite. The lava rock is unaccpetable because of contamination issues and possible metals in the rock.

mdm...
true plenum systems like the one Jaubert used provide much the same end result as a DSB, they convert nitrogen in an anerobic environment. They fell out of favor when the DSB craze hit about 5-6 years ago. If set up properly, they are every bit as efficient as a DSB in lowering nitrate levels, but have the advantage of not reyling on worms and such for water diffusion into the anerobic zone. The coarse media (3-6mm) combined with higher flow across the substrate than is possible with fine sand facilitate diffusion into the lower depths of the substrate. The stories you hear about them crashing are usually in systems where they were not set up properly, ie too fine a grade of substrate, inadequate water flow, excessive compaction of the substrate, plenum itself not set up properly, ect.

I've had good luck with my DSB thus far, but it won't be making the transfer into the new tank. The plenum system is a sound one, I'm going to give it a shot...

Mike

[mdmaquatic]

I understand that mike, i was just curious as it seems like a lot of work. I have done alot of volunteering work here in cleveland with the cleveland metroparks zoo and they have torn out all of their plenum systems. I hope it works out good for you.

[MikeS]

I hear ya Mike...

What kind of substrate did the Metroparks Zoo have above the plenum? Why did they decide to remove it? Selecting the proper grade of material for the substrate is very important. If the material is too fine, you'll suffer poor diffusion into the substrate and compaction/cementing issues. (cementing is another reason I'm going to avoid a crushed coral or agagonite substrate above the plenum). In addition, the more coarse substrate will allow for greater overall water flow volume in the tank than will be allowed with a fine sand.

The plenum, like the DSB, does have a lifespan, but if set up properly and maintained well, the effective lifespan can be quite a bit longer than a DSB. And it is more "renewable"....I'm going to install a pvc pipe in the plenum and cap it off, that way I can draw off the water in the plenum itself every year or two, effectively "renewing" the system.

The selection of live rock as the substrate was mojo's idea, (as was the initial suggestion to take a look at the older Jaubert style setups) and I agree with him. It makes perfect sense...The initial phospahte issues will be very minimal compared to aragonite or crushed coral, both of which are pretty well saturated with the stuff. Also, live rock will not chemically melt or cement, as will aragonite and CC, particularly in a tank using kalkwasser (which I use). The only two initial headaches will be breaking the live rock down to size...(tools required- a burlap sack, a concrete driveway, some manpower, and a seive)...but LR breaks up pretty easy. Headache #2 will be the cost...a bit more pricey than the aragonite or CC, plus some cure time in a tub in the basement. But these headaches far outweigh the benefits of using this as a substrate media IMO, and worth the extra time and money in the long run.

I have looked at many different substrate options for my new tank...and this one I think may be the best for my application...I still have a substrate for my LPS and clam, I get nitrate reduction that is as good if not better than a DSB, without many of the potential downsides of the DSB, and I have a system that has been proven in the past and can be a long term type of system in my new tank.

I'm going to move this to the advanced forum, I'd like others to weigh in as well...

Mike

[mdmaquatic]

Ok, sounds good. They removed it becasue of high nitrate problems. I do not remember the substrate sizes, but they did get alot of compaction and when they went to a DSB it seem to correct all of they're issues.

[MikeS]

If they were seeing high nitrate in these tanks, than likely there was simply not enough diffusion in and out of the substrate, and the system ceased to function properly. Any idea how old the plenum system was in the tank(s)? Systems like DSB's and plenums rarely stop reducing nitrates, quite the opposite, the anerobic zone has the potential to grow as it ages...so if they were seeing that, then something else was wrong....

Mike

[mdmaquatic]

Probably 12-15 years old.

[MikeS]

that's a long time....most people who use DSB's don't get that lifespan out of them...unless they have excellent flow, don't underfeed, and have a reletively low bioload, I doubt that they will see that kind of lifespan out of the newly installed DSB.

I'm still a DSB fan...but, it is what it is...it works well in some systems, in others it doesn't. While I doubt that the DSB will cause any kind of catastrophic failure in their tanks, I doubt it will remain unproblematic for 12-15 years either.

Mike

[gman0526]

I think it'll work, I can see the whole logic behind your thinking. :coolbeans:

Are you gonna try the mod. plenum or a straight Jaubert plenum? Do you plan on periodically "flush" it?
As you know I'm planning on a 75 myself ( :roll: yes another tank...) and this seems like a good alternative.

[MikeS]

it will be a plain old Jaubert style plenum...but I will plumb it so I can draw off it periodically...

Mike