Do green mithrax crabs eat....

[R.Kowalski]

coralline algae?

 

[wrightme43]

Not that I know of. I know diadema urchins love to eat it and make it spawn in your tank and go crazy covering every thing. Never heard of a crab that eats it.

 

[MikeS]

I have recently seen claims that some hermits will eat coralline, but the evidence presented to me did not convince me that is truely the case, there were a few other, more logical, explanations for the observed behavior...

MikeS

 

[R.Kowalski]

any suggestions ? and more info on my tank,

I have two mithrax crabs ,a dozen or so small to medium hermits,a blk sea star ,about 40 lbs of live rock, a lawnmower blenny, bicolor blenny, hepatus tang,and an african blue lined(or backed?) pseudochromis. There is also some sponge growing and several types of algae including something that may be caluerpa and some type of fan worm?Also trochis ,astrea ,and cerith snails.

My nutrient levels are all in the ideal range ,temp at 75 degrees F , and salinity at 1.024 . I have two compact fluoresccents 96 watts each on 3 1/2 hours off two then on four another 5 1/2 hours.

It looks like patches of coralline algae end up disappearing. Any ideas?

 

[steve-s]

I would think the coralline loss vs crab is merely coincidental. It's growth rates are really linked to how you maintain the chemistry and age of the set up, lighting is a small concern since coralline is fairly adaptive (color varies though). Once the coralline's been in the tank awhile the spores generally spread pretty easily as long as there's some kind of flow hitting the rock. If the coralline is showing little area's that look like patch's of peeling skin (like a person's sunburn), it's usually something amiss with the chemistry. Large patch's would indicate something changed (increased usually) in light intensity or the presence of a hitchiker urchin.

75° is also not the best range for a SW tank. You'd be better off somewhere in the neighboorhood of 78-80°.

I have two compact fluoresccents 96 watts each on 3 1/2 hours off two then on four another 5 1/2 hours.

Why the 2 hour off period in the middle?

Cheers
Steve

 

[R.Kowalski]

the two hour off period

The two hour off period was some advice I was given for interrupting the growth of green thread? algae.

I use the easy test strips for testing my tank. It says the nitrates and nitrites are in the ideal range, I forgot what the equivalents are for readings. I'll have to check the coralline algae more closely to see if they are peeling. I'll also keep my eyes open for urchins. Thanks.

Rick

 

[steve-s]

The two hour off period was some advice I was given for interrupting the growth of green thread? algae.

Reducing the photoperiod will help when adding/increasing lighting to prevent new algae growth but rarely does much when the algae has already established itself IME. With hair algae the best means of erradication is manual removal as often as possible. If you have a good amount of grazing snails (primarly turban species) they will keep it short. Most types of "cleaning animals" you will add will have a hard time with long growing algaes. If the algae is pruned by you as well, they will show much more interest in it. You need to also find the source of nutrient fueling it's growth. If the tanks been established for any length of time, I usually find food types used to be the culprit, primarily flake/dried. Increased frequencey of water changes with RO/DI water and a quality skimmer will also help.

I use the easy test strips for testing my tank. It says the nitrates and nitrites are in the ideal range, I forgot what the equivalents are for readings. I'll have to check the coralline algae more closely to see if they are peeling.

The ideal range for both of those is undetectable. Nitrites must be zero but the animals (depending on species) can tolerate nitrates to a degree, still a worthy goal to eliminate them.

I was not refering to that though when I asked about the chemistry although it wouldn't hurt to know the values. You need to find out what the alkalinity, Ca and possibley magnesium of your SW is. Alk and Ca will be the test kits you will use quite often so a worthy investment to get ones that are accurate, steer clear of test strip style for these. Magnesium is one I find rarely need testing except to confirm problem areas. If your LFS can test this for you it will save you some $$. More often than not poor coralline growth/die off is from improperly maintained chemistry.

How long has the tank been set up?

Cheers
Steve

 

[R.Kowalski]

I set it up in January. It has a peguin 330 filter,a seaclone100 protein skimmer, and a power head . I believe that I haven't been consistent of late with my weekly water changes (normally 4 gallon per week-40 gallon tank).My carbon may have expired as well so I changed it.

There are two types of caluerpa and atleast several species of different algaes growing in the tank along with the coralline algae. I use ro water for water changes. maybe I've been feeding more then I used to.

 

[steve-s]

a seaclone100 protein skimmer

Generally speaking this is a very poor choice in skimmers for efficiencey and performance. How much skimmate are you removing weekly?

There are two types of caluerpa and atleast several species of different algaes growing in the tank along with the coralline algae.

This will help with nutrient export only if the algaes are being harvested and tossed in the refuse on a regular basis. The nutrient remains bound up in the algae but if it dies some, the nutrient is released again so be sure you remove it instead. This will also help prevent it from reproducing sexually. Caulerpa's are not that well recommended to keep in the main system, personally I would opt for a non caulerpa species (caulerpacin problems) in a refugium application.

None of the above will have any bering on your coralline issue though. It will however help with your hair algae as long as the cultivated macro algae is able to outcompete the nuisance algae for the nutrient. Harvesting and tossing both will remove nutrient though.

I use ro water for water changes. maybe I've been feeding more then I used to.

RO water alone will not be sufficient when dealing with nuisance algaes. The membrane is not sufficient to remove PO4 and Si. Only a ion exchange resin/DI stage can do that. I would be worth the extra bit to add that. Home depot should have it for quite reasonable price.

Cheers
Steve