Mantis shrimp are cool, but saltwater is scary....

Greetings, saltwater keepers!
I've been keeping freshwater aquariums for a looong time, and have made several(often embarrassing) forays into the other side of the forum. I've looked into saltwater several times, and I've always come to the conclusion that saltwater costs too much and takes too much maintenance for a mildly ditzy and wildly inattentive fishkeeper like me, who struggled to keep live plants alive, much less maintain the delicate balance of chemicals and nutrients required in a saltwater setup. I decided I'd probably never get a saltwater setup, but I had one qualifier-I would keep a saltwater aquarium if I could somehow keep a mantis shrimp. I always said this jokingly, with a bit of a roll of the eyes, because I was under the impression that they were the type of animal that only a zoo or public aquarium could keep, because of all of their cool traits, like their punch and the crazy number of colors they can see. Imagine my surprise(and excitement) when a few days ago I stumbled upon a youtube video of a pet mantis shrimp. Turns out, you can keep mantis shrimp, and according to the websites I've perused, they are an easy saltwater creature to keep(sounds like an oxymoron, but ok). However, as I'm looking into maintaining a saltwater aquarium, I'm wondering if I still am in over my head. While I now an able to keep live plants very well, to the point of dosing daily supplements and maintaining a diy CO2 system, there is... a lot to unpack when it comes to saltwater and I can't find much material about keeping mantis shrimp, specifically. I'm thinking it would be a FOWLR type tank? It wouldn't happen until around september next year, so I've got time to figure it out.
TLR: Freshwater keeper will only get into hobby if she can keep a mantis shrimp but is confused.

Here's what I was thinking. Again, I'm not interested in getting into saltwater as a whole, I just have been infatuated with mantis shrimp for a long time:
20 gallon long tank
Live sand? Or maybe BDBS?
Some live rock
A freshwater plant LED designed for a 55 gallon aquarium mounted above both this tank and a freshwater tank
HOB filter mounted on the side of the aquarium, functioning like a powerhead?
A couple hermit crabs and snails, who I know will probably end up as live food at some point
One peacock mantis shrimp(or a different type, the peacocks are just really pretty)
Saltwater test kit
Saltwater mix(I'd be using tapwater)

Again, this would be several months in the future, after which I know I'd need several months to cycle. Is this a viable setup? With weekly 25% water changes, probably daily topoffs(Colorado=wicked evaporation), live food every so often but mostly thawed frozen shrimp and clams? I have no idea what I'm doing XD

 

Sounds like a plan. The 25% weekly water changes seem high. Note I never did freshwater. I know in saltwater many people are doing zero water changes with things like sump, macro algae (refugium), skimmers, algae scrubbers, and bio-pellets.
Personally I test weekly for nitrate and then determine what is best amount usually 10%, but lately i been moving towards no WC. Freshwater very easy and quick to do larger WC. With the salt water you need to purchase the salt, measure, and mix it, more time consuming and costly. I have corals so the water must mix overnight, and I use a ro/di machine. Whatever works for you. Good luck.

 

That’s easy enough. Mantis shrimp are hardy too. Feed them clams, silversides, and krill. Do 25% water change weekly with a small HOB filter and some live rock.

Only thing that concerns me a bit is the freshwater plant light. You’ll likely get algae growth.

 

Sounds like a plan. The 25% weekly water changes seem high. Note I never did freshwater. I know in saltwater many people are doing zero water changes with things like sump, macro algae (refugium), skimmers, algae scrubbers, and bio-pellets.
Personally I test weekly for nitrate and then determine what is best amount usually 10%, but lately i been moving towards no WC. Freshwater very easy and quick to do larger WC. With the salt water you need to purchase the salt, measure, and mix it, more time consuming and costly. I have corals so the water must mix overnight, and I use a ro/di machine. Whatever works for you. Good luck.

I've read about those pieces of technology, but they all seem pretty expensive... If I were to do this, I don't want to invest that much into it. No interest in corals or anything here, just a deep fascination with mantis shrimp

That’s easy enough. Mantis shrimp are hardy too. Feed them clams, silversides, and krill. Do 25% water change weekly with a small HOB filter and some live rock.

Only thing that concerns me a bit is the freshwater plant light. You’ll likely get algae growth.

Might using a smaller light on night mode(blue LEDs) be a better idea? I have read that using a lower level of light is good if you want to see more activity, and since it's just be a FOWLR, would that work better?

Thanks so much for the feedback! Just trying to figure everything out-there are so many different sources out there and very few of them have anything to do with mantis shrimp. Thanks!

 

Honestly any light or even no light at all is fine. A Mantis doesn’t need any light that’s just for your viewing pleasure.

 

As mentioned big difference between something like a fish only (or in this case Mantis Shrimp only) tank and one loaded with SPS Corals (considered the most demanding corals in the hobby). Other than more frequent water changes, using RODI Water to avoid algae issues and keeping salinity levels balanced it's no different then than keeping a freshwater tank.

 

These things look amazing! How am I just hearing of them?

 

So is RODI water pretty necessary then? I was hoping to get by with just tap water, but if it's that important I could probably do it.

 

So is RODI water pretty necessary then? I was hoping to get by with just tap water, but if it's that important I could probably do it.

The problem is that when you combine your average municipal tapwater with the highly mineralized salt crystals, at the very least it creates the perfect storm for unwanted algae growth (ie green hair algae) at best and at worst can contain minerals and solids that are harmful to marine life (prime can detoxify but it can't actually remove the source unlike RODI). Also IMHO it's a presentation thing. The water is almost always much clearer and looks better for display with RODI. I recently did an experiment with my freshwater tank where I went from straight tap to a 50/50 treated tap/RODI water mix and the water has definitely improved for clarity. You can either buy your own system and make your own for fairly cheap (ie Aquatic Life RO Buddie for $60 on Amazon) or you can get it from a local fish store. Given the smaller sized tank (ie 20 gallons) you would only need a max of about 10 gallons per week (3-5 gallons for partial water change, 5 gallons max for RODI top off for evaporation).