Easier way to change out crushed coral for dsb?

[richtpe]

I bought an established 55 gal a little over a year ago that didn't have much sand in it. The "expert" that arranged the purchase for me put about a 2 1/2" bed of crushed coral in it before we set up all the rock and corals. I've since added a bunch of corals and a couple of clams that are generally all doing well. My problem is I keep getting brown algae (diatoms?) and some cyano building up on the crushed coral every week, which I siphon off during water changes. Water parameters (i.e. ammonia, nitrite, nitrate, phosphate, silicate) are all ok (I have done redundant tests with different kits for all except the silicate). From reading the great info on this board, I'm thinking I'd like to replace the crushed coral with a dsb (I plan on going to Home Depot & WalMart this weekend to see what kind of play sands they have there).

My question is whether there's an easier way to change out the c.c. than tearing down the whole tank. I know I've read several posts from the experienced members (thank you OrionGirl) that recommend tearing down the tank, putting the c.c. in nylon bags to seed the new sand, and gradually removing the nylon bags. However, I'd rather not tear down the whole tank, mostly because of the corals, clams, anemones being well attached to the rock and am scared of damaging them in the process (also everything is set up now the way I like it).

What I'd like to do is gradually switch out the c.c. with sand over a period of a couple of months. Meaning that with each weekly water change, I'd siphon out some of the c.c., then place some sand in the tank (by pouring it through a tube to get it to the bottom with minimal clouding of the water), the sand would work it's way to the bottom of the c.c. during the week, and I would repeat the process again. The sand would then become seeded by the c.c. that remains in there and also help to seed the sand I put in during subsequent changes. This, of course, being my unproven theory, which is why I'm here.

Any thoughts or comments on this method would be greatly appreciated. For reference, I've got about 100 - 125 lbs of rock, Aqua C Remora skimmer, phosban reactor, emporer bio-wheel, 4x65W Orbit PC light, one SPS coral, numerous polyps, mushrooms, and LPS, leather, 2 anemones, 2 clowns, 2 wrasses, a blue tang and a purple tang (another one of the "expert's" recommendations - they do get along well and I am prepared to give one to a friend with a larger tank if needed) and a blue spotted goby. Also about 7 snails (believe they're Astraea) and 10 blue legged and red legged hermit crabs.

 

[OrionGirl]

Can you do it this way? Yes. Even using a tube, though, you will still get some clouding, more than if you fill on top of the sand. And, depending on how the rock is in the tank, you risk toppling the existing live rock as the crushed coral is removed. Toppling rock is much, much worse than you pulling everything out, not only for the inhabitants, but potentially for the tank. If the rock is actually sitting on top of the CC, rather than on base rock buried in the CC, I definitely would not risk it.

 

[richtpe]

Thanks very much for the quick reply. The rock is pretty much all sitting on the glass bottom with the c.c. in around the base of it. I should probably also tell you that the c.c. bed isn't even throughout the tank, and goes from about 1" deep to about 2 1/2" deep in places.

Would it be best if I just bit the bullet and tore everything down this weekend and replaced all the c.c. at once (using your suggestion of putting it in nylon bags to seed the sand)? Am I placing the livestock in a lot of danger doing this? If I do tear it down, would I need to detach corals & anenomes from the rocks? I know the mushrooms, clams, anemones, and the red lobo are pretty well attached now.

Even using a tube, though, you will still get some clouding, more than if you fill on top of the sand

Not sure what you mean by "fill on top of the sand". Could you clarify?

Sorry for all of the questions, but I am nervous about doing this and you are a great help (even when I'm not asking the questions myself).

Thanks much!

 

[OrionGirl]

No, you'll remove everything from the tank, and pulling the rock, with attached critters and all, it normally not a big deal. You have to be careful to establish that the animal is attached to a single rock--if not, you need to move both rocks at the same time to prevent injury. I've done it a number of times without losing a single animal. I have a couple of large tubs that I fill about 1/2 up with new SW, move the animals and rocks, fill up the rest of the way, and cover to prevent jumpers (in or out--I have cats that help).

Here's how I go about the setup. I put in the base rock that will be buried. I fill in the sand around, making sure the sand fills in all the crevices. Then I put a large plate on the sand, and start filling the tank with the hose hitting the plate. This reduces the disturbance to the sand, so very little gets caught up in the water column. Once the tank is about 3/4 full, I setup the power heads and such, and start up the heaters. Once the tank is at the same temp as the tubs with my rocks and critters (or at least really close), I start putting the live rock and corals back in the tank. Once they are all in, I add the rest of the water, and put the fish and inverts back in the tank. This gives me time to move rocks or coral around without worrying about squishing a fish, or stressing them even more.

 

[richtpe]

Awesome. I think you may be giving me the confidence I need to get this done right...pending a few more nervous questions of course (sorry). I'm probably going to repeat what you've already told me, but would like to make sure I'm understanding everything.

What I'm thinking (from what you wrote) is to get a few large plastic tubs from WalMart (20 gal or so?) and fill them halfway with new water (getting the temp and salinity as close to the tank as possible). Put the rocks and critters into the tubs and fill up the rest of the way with tank water. Drain any remaining water from the tank into another tub (going to call this the "spare tank water"). Scoop all the c.c. out of the tank and put into nylon bags and put them into one of the tubs.

Getting everything back in poses some questions for me. I don't really have any base rock, and most of my live rock is large and has critters attached. So I'll put in whatever rock pieces that don't have anything attached (and that make sense based on how I want the tank aqua-scaped) - which won't be much probably. I'll then put in the sand and fill first with the "spare tank water" and then new water until until the tank is about 3/4 full (using the plate method you mentioned). After getting temp and salinity in the tank to match the tubs, I'll start putting the rest of the rock in. For the rocks on the bottom, I'll drive them (gently of course) into the sand by twisting and pushing until they are solidly resting on the glass tank bottom & stable, then fill in the sand around the rock's base. I'll then put in the fish and fill the tank the rest of the way up with the tank water I had in the tubs storing the rocks & critters. Then place the nylon bags with the c.c. on the bottom (any trick on where to place these or do I just have a bunch of small bags along the whole bottom? Should I bury them partially in the sand?). Then sit back and enjoy? hopefully?

Do you know about how much sand (i.e. how many bags or how much weight)would be needed for a 55 gal? I'm thinking I need about 2 1/2 to 3 inches deep? Or do I need deeper?

Thanks so much for your help and again I'm sorry if I'm just repeating a lot of what you've already said. I just want to make sure I completely understand and not hurt any of my buddies during this process.

 

[OrionGirl]

Yep, walmart has tubs that will work just fine. I prefer round tubs, but that's just me. Anything that will hold water and is clean will work.

Instead of trying to push the rocks in, I'd just plan on picking up a few chunks of base rock--dry tufa, 'lava', or any porous stone will work, and it will be hidden by the other rocks and sand, so appearance counts less than shape. Blocky rock that gives a good stacking surface is best.

For the bags--stash them in some current, to push the water through, and on the sand--I wouldn't bury them at all, just rest on top. When I made the switch, I put a few in the tank, and the rest went in my sump--basically you want them to be easy to remove.

Have a plan for getting the watr back into the main tank. It's sometimes tough to place the tubs where you'll be able to siphon the water back out of them, so see if you can setup a power head to do the work for you. The key is to go slow, and have the water trickle in, rather than splash in. I've done it with buckets, but I promise you--you will get tired holding the buckets up to carefully pour water in within about 20 gallons. At least, I did--and I'm a strapping lass. .

For depth--around 3 inches is good. I'd figure on having about 100-120 pounds of sand, which I think would be around 2 bags. I honestly don't recall how many bags I put in my 120's, but there's also about 6 inches in both of them.

 

[richtpe]

Great. Think I'm going shopping tonight. :dance2:

Any suggestions on where to pick up the base rock you spoke of? Could I use some of the dry, porous stuff I think I've seen at PetCo or do I need to get rock (live I guess) from the LFS? I'm assuming that bricks wouldn't cut it?

I already use a powerhead to get water in during changes, so I'm all set there (I hear ya about getting tired holding buckets).

 

[OrionGirl]

Yep, the dry, porous stuff from Petco will be dandy. The bacteria and such will quickly colonize the rock, adding to the biofiltration of the tank, without the sticker shock of live rock. Bricks: depends--I've seen tufa that has been cut into a brick shape, and it will work fine. Landscaping bricks--might, but I'd be leary that they were treated somehow, or had been exposed to a chemical that might leach out.

 

[richtpe]

Thanks again! I'm also thinking about using pvc pipe to build a framework for the live rock to sit on (instead of buying base rock). Any experience or thoughts on that?

 

[OrionGirl]

No experience, and just one story. A member of ReefCentral had a large framework of PVC in a big tank--think it was a 180. After several years, he started losing corals--looked like predation, but none of the fish or inverts seemed a likely gulprit. Finally did a night watch, and discovered an enormous predatory segmented worm that was living in the framework--using it as a private maze, and coming out at night to graze. The thing was something like 4 foot long, huge. Gross. So--the framing will work, but I'd fill them with water, and then put on caps, seal joints, etc, to prevent the interior from becoming an unwanted pests home.

Another option--and I have done this--is to create a floating platform. I used eggcrate (like they put in fluorescent ceiling lights), cut to the desired shape, and chunks of PVC for legs. Zip stripped the legs to the eggcrate, and then stacked all the rock on top. The rockwork sat about an inch above the sandbed, plenty of room for cleaners to get in and remove solid wastes, and the rock overhang enough that you couldn't see the eggcrate. Did away with it because sometimes you could still tell that the rock wasn't sitting on the sand--looked kind of odd, but setting the eggcrate framework down, then filling in with sand to be level with the top would work just as well with no floating effect.