• Looking to buy a cephalopod? Check out Tomh's Cephs Forum, and this post in particular shares important info about our policies as it relates to responsible ceph-keeping.

Mercatoris care tips

Yes, a red lens will work as long as it does not "leak" white light from the sides (black tape can help here, I used pieces of opaque acrylic on one set up.

Be aware that the grills for water to enter the filtration area are subject to an octopus in the sump. The all-in-ones are very susceptible to this as the back area is an inviting dark spot. It MAY help to keep your live rock centered and off the back wall but placing a VERY coarse (to allow flow) sponge behind much of the overflow area may be required.
 
You need to make it easy to clean as well as monitor (to avoid overflowing the aquarium). Mesh will work but suffers from being blocked quickly so if you rig something with it be sure you have at least 2 screens available and swap them out with each water change (in addition to monitoring daily).
 
YMMV, but they produce a lot of waste and smaller, more frequent changes tends to be less stress on marine aquaria than larger less frequent. Others with more recent experiences can weigh in here, but I aim for 10 to 15% changes weekly. I tried a regimen recently with a bigger change every 2 to 3 weeks based on testing the water frequently and basically just ended up with a green hair algae explosion to show for it.
 
I hope your system is buying RO/DI water ...RO to remove the chemicals and pollutants and DI to remove the minerals and metals. At this stage of your experience, inventing your own method is not a wise choice. Most saltwater fish stores will sell RO/Di water and will reduce the price if you bring your own container. You will need both FRESH RO/DI water to top off the evaporated water and SALT RO/DI (which you can mix using salt made for the hobby or purchase) for water changes.

Fiddlers can be kept in a bucket or any spare plastic container with relatively tall sides (they tend to escape if the sides are short). I find it easiest to keep them in shallow saltwater (you can use the water you remove from your tank during water changes) with a pile of rocks or other items placed in the center of the container to allow them to come out of the water. They can be kept in damp sand with a "swimming pool" but this tends to be hard to clean and will smell more quickly. Change the water weekly or if you detect a smell and remove any dead animals ASAP.
 
Yeah, my system was buying RO from the store. You can't use tap water with these guys. After a few months of changes, I ended up spending more than I would've just buying the RO unit. And believe me , I'm the king of saltwater on a budget here. Check out eBay for stuff like that. I got one some time back for about $50, and you can even find some brand new ones for ~$130
 

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