new 90g seahorse/jawfish/softie/macro build


New member
Hey folks, new member. I'm getting ready to start a new 90 gallon (or 75 if I can't find a 90g (which is proving rather difficult)) tank build/setup and would love any constructive feedback, suggestions, or comments from all the knowledgeable folks here. Maybe a decade a go I helped my roommate setup a 40 gal saltwater tank over a couple years. Other than that my experience is limited to reading plenty online and watching same buddy upgrade to a 125 when I no longer lived with him.

In the tank I intend to keep:
  • a couple or few seahorses - aquacultured
  • jawfishes (4 maybe? ideally at least 1 pair)
  • macroalgae
  • softies (xenia, I dunno what else)
  • a photosynthetic gorgonian perhaps
  • as many copepods as I can get to live in there

My plan for the tank setup is the following:
  • I'm building a custom stand from what seems to be a famous thread on the topic on this site
  • A drilled overflow box with herbie or bean animal flowing into:
  • a sump (29 or 40 breeder?) containing:
    1. 1 low flow refugium/copepod farm/inline fry rearing section with sand, live rock, and macros
    2. 1 high flow chaeto tumbler section
    3. return pump section (2 pumps perhaps for redundancy)
    4. no skimmer
    5. led lights above fuge and chaeto section on opposite cycle of display tank
    6. bag of carbon somewhere in there
    7. ATO either in tank section or in a separate 5gal bucket if using a smaller tank
  • display tank containing:
    1. 4-6 in deep sand bed - not purchased live
    2. live rock (not purchased live, avoiding pests) - not a ton, shooting for a negative space scape
    3. macros
    4. a powerhead or two
    5. led lighting strip, nothing wild, considering the Current USA Orbit Marine

I'm planning on using a lazy man's triton method, by which I mean I'm not keeping any stony corals so I'm not going to go nuts about dosing or testing for elements but will do some and take lightly mostly to reduce the amount of water changes needed. Every 2 weeks, maybe once a month is possible?

I'm not sure what else I'm forgetting to mention, either because I'm not thinking of it now it or haven't thought of it at all. Let me know what I might not be considering but should, I appreciate any input! Looking forward to joining the forums and hopefully will have some success to share sometime in the not to distant future.

Michael Hoaster

Registered Seaweedist
Premium Member
This sounds like a great project!

I have some experience with macro algae and seagrasses, so I have some thoughts that may help. First, if your display is going to be dominated with macros, you don't really need any planted refugiums. I see you want one for pods and fry, which should work well, but I wouldn't bother with a second fuge for chaeto. Why? Because they'll be competing for nutrients. What good is a hidden chaeto ball that's thriving, if your display isn't? You'll find that macros can be greedy little piggies and strip your water of nutrients quickly, so you want your display to have priority.

Starting with dry rock is asking for algae problems. It's a blank canvas for them. Consider at least mixing in a little live rock. will sell you as little as ten pounds of farmed live rock, with shipping included in the price. If you're afraid of aiptasia anemones, just add some peppermint shrimp. Any (unwanted) algae that pops up should be promptly removed in the earliest stages, so it can't get established. I found I got some quite desirable macros pop out of my rocks, and I still keep them.

After setting up the tank, cycle it with no lights on. That's one to two months. Why? Because in the earliest stages of development, you want the 'good' nitrifying bacteria to form. If you light the tank, it will encourage algae-friendly bacteria to form, which will put you into the ugly phase pretty quickly. By not lighting the tank, you can avoid the early ugly phase altogether, and discourage algae in the long term as well. It's very tricky to get rid of pest algae, while at the same time trying to get your chosen macros to grow.

Do you have experience with seahorses? They are very challenging and need very low nutrient levels to prevent illness. Macros need high nutrient levels. That's going to make things very difficult. If you're dead-set on seahorses, I'd suggest going with seagrasses instead of macros, since they don't require high nutrients. There are easier alternatives to ponies, like pipe fish and file fish.

I hope I haven't discouraged you. I want you to succeed. I'd suggest you do some research and figure out what your priorities are, so you can avoid a struggle. Macro algae tanks can be easy and a lot of fun!


New member
Hi Michael, thanks for the reply, much appreciated. You have addressed one of my main concerns that I've been thinking of over the last few days, that I will only be able to support so much macro without dosing nitrates and phosphates and more isn't necessarily better or sustainable. I may opt to do fewer or no macro and focus more on softies in the display but want good hitches for horses and really like the bright red look of some macros.

One of the main drivers for the division of chaeto and separate macro fuge is to have a high flow and low flow areas of the sump, with the flow rate of the low flow section adjustable with a valve, giving a slow area for detritus to settle out and become copepod food and also letting me slow it way down if I want to attempt to raise fry inline. The high flow chaeto makes sure I get enough turnover and flow over some macroalgae even if I have the low flow turned down real low. Maybe if I have macros in the display tank already this isn't as big a concern.

Regarding the ugly stage, yes I plan to cycle unlit, and I was planning on dosing with bottled good bacteria, though I'm not certain it's not snake oil, as well as with coraline cultures once the lights go on to get things off to a good start.

I maybe would consider a bit of farmed live rock but have some trepidation, I like the idea of never introducing any pests. I appreciate that link though, I'll check it out.

No, I'm new to horses and yes I'm dead set on them, but could pivot away from the macros in display if needed (I'd still want some in fuge for nutrient export right?) But that's good advice that I'll need to keep a keen eye on the nutrient balance if I hope to keep both happy.

Thanks again for feedback. Step one of the tank build is complete, sistering the floor joist where the tank will go. Next up is acquiring a tank and building the stand.