Pods gone from DSB, now on rocks + air bubbles

[blenny100]

My tank is about 6 months old. For the past month or so, I've noticed fewer and fewer pods on the sand bed, but more pods on the live rock.

It used to be that I could look at any given area of the sand bed (after lights out) and see many creatures crawling around. Now, I see a few, but lots on the rocks.

In addition, I've been experiencing some cyano outbreak (not much, but some -- 6-8 sq. inches total in a 120G tank) on the DSB.

I measure for Ammonia, Nitrites and Nitrates and they are undetectable.

Also, wherever there is cyano (or just regular algae growth) on the sand bed and rock, there are air bubbles that seem to come out of the algae. They are kind of trapped on the surface of the algae mat -- then "squeeze" their way up. Is this a bad thing?



Any help would be appreciated.

[capncapo]

The bubbles are expected with cyano.

Did you add criitters ( detritivore kits ) to your sandbed when you set it up? If not, the bed is not complete and will be nothing but trouble.

You may also need to incease the amount of flow in your tank.

All of this assumes that your sand is of the proper particle size distribution.

I would recommend that you read the following information contained in the two sticky threads near the top of the forum page:

http://archive.reefcentral.com/forum...hreadid=118418

http://archive.reefcentral.com/forum...hreadid=687314

[blenny100]

Capncapo -

Thanks for the reply. I did try to be very careful when setting up the tank -- and follow the suggested DSB guidelines. My DSB composition is as follows:

Total sand ~300 lbs, enough for 4" in main tank and 1-2" in sump (mainly as a refugium for the critters)

Sand particle distribution

120 lbs 0.22 - 0.11mm
90 lbs 0.27 - 0.14mm
45 lbs 0.51 - 0.27mm
30 lbs 0.92 - 0.43mm

Composition

Si O2 98.20%
Fe2 O3 <0.50%
Al2 O3 <0.50%
Ti O2 <0.50%
Ca O <0.50%
Mg O <0.50%
K2 O <0.50%
Na2 O <0.50%

In addition, I purchased 2 sets of DSB starter kits from IPSF.COM, as well as "live sand" from Bills Reef.com (both of which are recommended on this forum). You do raise a good point though -- I wonder if these have specifically included detritovores. My understanding is that these are worms, as opposed to just pods. I do see quite a few worms in the tank (they are half red/half black-ish with hairs growing all over) -- perhaps, their aren't enough on the sand bed?

In addition, the cyano may be aggravated by a switch about 1 month ago to a fresh food cocktail of shrimps/squid/scallops -- and a switch about a week ago to E. Bornmeman's coral food cocktail.

Any further thoughts would be appreciated - Thanks!

[rshimek]

Hi,

See the sticky thread near the top of the forum listings about "Red slime algae, cyanobacteria...."

If the sand bed was set up properly, and yours appears to be more or less properly set up, although the sediments are coarser than is optimum, the bed will need a while - up to six months or more to become fully functional. If the tank is rapidly stocked, the ability of the organisms in the developing sand bed to utilize the nutrients will be rapidly outstripped and this can result in a cyanobacterial outbreak.

Also, some fishes and inverts will prey on organisms in the sand bed degrading its functionality. Hermit crabs, peppermint shrimp, any kind of sand sifting organisms will all whack the bed severely.

My guess is that the nutrients have accumulated faster than the organisms in the bed have reproduced. So... follow the guidelines in the linked sticky thread.

If you have any specific questions I try to answer them.

[blenny100]

Thanks for the reply. We have had the bed functioning for about 6-7 months now, and have been careful not to include any of the things you've warned about in your articles.

Current contents are:

1 Purple tang
1 Hippo tang
1 Tomato Clown
1 Cardinal (Pterapogon kauderni)
1 bi-color blenny (Ecsenius bicolor)
1 flame angel

We specifically avoided all kinds of hermit crabs in the critter kits. Unfortunately, we just discovered one "hairy" crab that we need to capture.

Specific questions we have are:

1) Seems like more pods on rocks than on DSB. Is this just happenstance? ie., if we see pods on the rocks, then they are also on the DSB, we just don't see them when we happen to look?

2) What exactly is included in the "detritovore" term that is used? We are assuming it is a common term refering to pods and worms. Is this right? Or is there some specific animal / critter we need to get that we're missing. Currently, we bought the following: IPSF.COM's kit which include Reef amphipods and Hawaiian Strombus Grazers, as well as 10lbs of "Live Sand" from BillsReef.com. We see pods running around, as well as "worms" -- half red/black hairy things.

These were added into the tank when it was "empty" -- just live rock and sand. We let the DSB populate for close to 2-3 months before adding anything new.

3) Will the "hairy" crab -- about 1.5" in diameter kill pods? For some reason, we don't see many pods in the immediate vicinity of the crab's rock -- and so suspect that this may be a problem.

Thanks!

[capncapo]

It is a definite possibility that your detritivore kits ended up as crab food and that you have very few detritivores left. Hence, the issue with the sandbed.

Put your crab in a species tank or find it another home if you want a working DSB. You might want to replenish your supply of critters.

[rshimek]

Originally posted by blenny100

Hi,

1) Seems like more pods on rocks than on DSB. Is this just happenstance? ie., if we see pods on the rocks, then they are also on the DSB, we just don't see them when we happen to look?

Well, it is hard telling what you mean by "pods," that garbage term covers a multitude of sins, but I suspect you mean small crustaceans. There are a lot of different types of these. Some live more on rocks than sand, and this may be what you are seeing.

However, there are probably small crustaceans living in the sand bed that you might not be seeing. Additionally, most of the sand bed bugs are active after dark, so you may wish to do a couple of "night dives" and see if you can see things on/in the sand.

2) What exactly is included in the "detritovore" term that is used?

See this article for a discussion of this term and examples of some of the animals involved.

3) Will the "hairy" crab -- about 1.5" in diameter kill pods?

Very definitely! These crabs are disaster in reef tanks, see here.