Coldwater Marine Tank (Local Species)

[fc004]

Hey guys,
I’m thinking about setting up a coldwater sea tank (biotope of my coastal area here in Portugal) but am completely new to saltwater tanks (only have worked with freshwater tropical fish). Im thinking of a tank that will hold around 50 gallons, but have no idea on the filtering equipment and saltwater change dynamic. (Also won’t buy a tank refrigerator yet as temperatures can be easily kept at 20°C and i can buy a fan for the summertime). Can you guys care to explain me if there are differences to the tropical saltwater scenario? Will I need a SUMP, skimmer, power head...??
Also, what is different between a tropical and coldwater tank (besides the obvious), is there any type of osmoregulation equipment that can allow me to surpass water changes (and the constant need to get water from the beach), any salt mix that would work.

I feel quite overwhelmed but am willing to patiently learn from what you experienced forum people are willing to teach me Thxx In advance!!

[Autumnsky]

Are you thinking of a lagoon type tank? Like a tide pool?

The 50G size may seem large thinking of freshwater, but for most ocean fish in saltwater you need 200 +Gallons because they get so big!

You could do something with coral though, more like a reef. And learn which types you might want to try from your area there, and just verify what size things need.

For me personally, I like certain macroalgae, smaller tanks and no sump (HOB filter) with little fish (largest being a Clown fish) and special shrimp (Anemone shrimp), crabs like pompom and Rock Flower Anemones.

Do you have a few species of fish in mind from your area?

[fc004]

Originally Posted by Autumnsky

Are you thinking of a lagoon type tank? Like a tide pool?

The 50G size may seem large thinking of freshwater, but for most ocean fish in saltwater you need 200 +Gallons because they get so big!

You could do something with coral though, more like a reef. And learn which types you might want to try from your area there, and just verify what size things need.

For me personally, I like certain macroalgae, smaller tanks and no sump (HOB filter) with little fish (largest being a Clown fish) and special shrimp (Anemone shrimp), crabs like pompom and Rock Flower Anemones.

Do you have a few species of fish in mind from your area?

gobius niger (goby)
gobius paganellus (goby)
palaemon serratus(shrimp)
palaemon elagans (rockpool shrimp)
palaemonetes varians (another shrimp)
diplodus puntazzo(white seabream)
parablennius gattorugine (big goby)
lipophrys pholis (sand goby)
parablennius pilicornis (crested goby)
coryphoblennius galerita (goby)
pomatoschitus minutus (goby)
invertebrates/molluscs:
actinia equina (morango do mar)
gubilla umbilicalis (sea snail)
anemonia sulcata (anemone)
seaweed:
ulva rigida (sea lettuce)
fucus vesiculosus (bladder wrack)
codium tomentosum (velvet horn)
others...

So I was really thinking of a kind of rockpool scenario where the biggest fish will be the diplodus puntazzo (just so the water column is somewhat occupied). As for a 50 gallon tank (already have the place and stand for it) do you think a skimmer and HOB filter is enough? That would be cool since I already have experience with this kind of filter, can you recommend any? (Will probably try out with a bigger tank sooner or later but 50 gallon is one of the only certainties of an idea I’ve had for a long time) Cheers!