New to freshwater fish hobby!

Hey everybody!
I'm new to the freshwater fish hobby. I've been a saltwater tank keeper for many years although I've been out of the hobby for for the last 5+ years. So I thought I would try my hand at keeping a freshwater tank.
Let me tell you a little bit about myself: The first tank I had was a 36 gallon bowfront tank with an HOB filter. That ended up a disaster because I just jumped in with both feet, doing very little research (About three days worth actually) and taking all the advice of my LFS. I made every mistake imaginable beginning with not cycling the tank, not even seeding the tank, no live rock (fake decor only) and just plopping in four Domino Damsels and a Banded Coral Shrimp with very little acclimation time. I was very proud of myself because I had just created my very first saltwater tank.
Needles to say, everything when south really fast in the next few days, starting with the pincers just falling off my Coral Shrimp. He acted very lethargic after that and the next day stopped moving around entirely. I reached in with my fish net to give him a nudge and he just fell off the fake rock he had perched himself on. When he hit the gravel, (Yes, I said gravel) he broke up into several pieces. I decide this was not my doing and that the LFS had sold me a bad shrimp. Meanwhile the Damsels were going spastic and started attacking anything and everything that was in my tank. Two of them disappeared and the other two just went belly up at the top of my tank. The tank had crashed big time. I later found the first two wedged under my expensive fake decor. It was then I knew it was something I had done (Or didn't do).
I tore the tank down and left it empty to decide whether or not I had chosen the right hobby. I started to do a little research to see if I could find out what had gone wrong with my tank.
That's when I read about cycling a saltwater tank. Days of research turned into weeks of research which turned into months of research. I had become a sponge, reading and studying everything I could about saltwater tanks and fish keeping. I bought books on water quality and Algae control. I read every article I could find online about salt gravity, calcium levels and tank mates for a 30+ gallon tank. I joined a couple of respected saltwater forums and started asking questions. Lots and lots of questions. I found a marine scientist, a professor of marine biology and an aquarist in these forums who had each been in the hobby between 20 to 40 years and read every thread they had posted on the hobby and their experiences in fish keeping. Then I started asking them questions. They took me under their fins (pun intended) and mentored me for the next several months.
Finally, I felt confident enough to restart my 36 gallon tank. I kept the HOB filter and added an HOB protein skimmer, powerheads, LED lights and a good quality heater. I ordered a few pounds of live rock online was lucky enough that I had an aquarium equipment supply warehouse 5 miles from home where I bought a couple bags of live sand and a marine test kit. I got a couple of RubberMaid garbage cans, filled them with RO water and using some inexpensive powerheads to mix the water, I added marine salt to a specific gravity and just let it churn till the live rock and sand came in.
The day was finally here. I placed the live rocks on the bottom of the tank, added the live sand and, putting a dinner plate in the tank, slowly added saltwater till the tank was full. I turned on the powerheads and waited for the tank to clear before I turned on the HOB filter. To kick start the cycle, I took a small piece of raw shrimp, tied it up in a piece of nylon bag, tossed it in and waited.
In an attempt to make a long story short(ish) I'll just say that I let the tank cycle for a month before I added a CUC and let it cycle for another month before I added my first fish. I think that I was pretty successful in my second attempt in the saltwater hobby.
Now I'll move on because I know you must be getting bored by now.
The last tank I kept was a 72 gallon bowfront with a 30 gallon sump/refugium. I built this tank from the ground up, including the custom stand. It took me over a year to build this system. The stand was 72" wide x 72" tall and came apart in four pieces not including the tank, sump and equipment. It had a base, two side towers that sat on the base at either end and a canopy that sat on the towers. The base had room for the 30g sump which held the return pump, an in-tank protein skimmer two digitally controlled water heaters, a custom up-flow algae scrubber and all my filter media. It even included a hardwired electrical system with a breaker box, three GFCI outlets and light switches to control each outlet. (See attached photos). To make another long story short, I'm a big fan of invertebrates so I kept Serpent Stars, shrimp, a lobster, hermit crabs, crabs, snails, urchins and a small assortment of soft coral as my primary livestock. I did have a clown fish and a watchman goby to help keep the beneficial bacteria established. These two became inseparable tank mates.
The whole system sat on a concrete floor so weight was never a problem. With everything up and running I estimated the weight to have been close to 1,000lbs. Maybe more.
Well, a little over a year with the tank running (and not losing one critter in all that time) I ended up getting a divorce and had to sell the house and move into an apartment. Sadly, the tank had to go. I donated all my livestock, sand and rock to my favorite LFS, broke everything down and sold it all, lock stock and barrel. I was pretty depressed and didn't think I would be able to spend the time to maintain even a smaller tank so, I decided to get out of the hobby. I still handed out advice, when asked, in a saltwater fish forum that I was a long standing member of but eventually, even that stopped. Just today, I visited that same forum and found that all my threads and posts are still listed. Made me feel pretty good about what I had accomplished as a saltwater hobbyist.

Now, after seven years of being in the saltwater hobby and 5 years of being out of the hobby, I thought that I would throw my line back in the water and try my hand at being a freshwater fish keeper. I know that I can bring a lot of my saltwater hobby experience to the freshwater hobby but I also know that I need to do months of research before I can start putting equipment together to build my very first freshwater tank. I was thinking of starting with a 55 gallon tank. Any thoughts?
I hope this the beginning of a long and fruitful journey to becoming a freshwater hobbyist and talking to many of you and reading all your threads here, in this forum and asking for advice so get ready for tons of questions from this newbie.
I look forward to all your advice and knowledge. As they say in the saltwater world, "Nothing good happens fast in this hobby".
A closeup of the tank.

 

Starting with a 55 is a pretty good choice. The main difference between sw and fw tanks is that you have less things to worry about with fw. Most of your filtration theory will be the same but you won't need a protein skimmer or aged water, just a bottle of dechlorinator and tap water is fine for most. If you want ease of maintenance (filter changes) then a hob filter would be easier but I prefer canister filters because they are pretty much silent and require less interaction over time, they also show less mechanical in the tank. Some Forza canister filters (expensive but recommended) come with built-in uv which you can turn off at will so there will be less ugly mechanical stuff in your tank. If you want to do plants plan to spend a good chunk of your money on a high quality light with a built in timer. It's good to decide what kind of stocking you're wanting to do before building everything as some fish will not get along with plants (they'll tear them up or eat them). I'm still new to this particular forum but everyone seems nice here so don't be afraid to ask questions. Hope this helps.

 

I was planning on including a 20-30g sump in the cabinet below to house most of my equipment (specifically heaters) to keep the tank as uncluttered as possible. Hopefully putting the HOB in there and a few live plants for filtration

 

I have something similar on my 150 gallon. I have a love hate relationship with the sump portion. Is the tank you're planning on going to be drilled? If your planning to do hob overflows instead of drilled be warned getting it quiet is a chore and a half. I've been messing with mine for over a year and still find it to be too loud. Wish I could go back and tell myself to just drill it or go with dual canisters

 

I plan on going with a predrilled unit with internal overflows and an internal pump in the sump (hey, that rhymes! Sounds a little dirty, but it rhymes!) for the return. I don't like anything sitting outside the sump and I don't trust HOB overflows because of syphoning dangers if the power goes out and/or the return pump fails. I've always been a big fan of sumps/refug's. It just gives you so many more options of what you can do. Not to mention the extra water volume helps keep the parameters in check. With a sump, you can put 90% of the equipment in there, so the only eye sore in the tank are the powerheads. I like my tanks to look as natural as possible.
Is your 150 glass or acrylic? Either way, it could still be drilled. During my 72 bowfront build, I bought an old 75g glass tank that had a blown seam in it, just to practice drilling for overflows. Damned thing looked like swiss cheese by the time I was done with it. Only used one diamond bit by drilling slow, using plenty of water to keep the bit cool and a template to keep the bit centered.

 

It's glass otherwise I would have drilled it but at the time I was replacing the previous tank that had a catastrophic failure and I couldn't afford to buy it twice if the worst happened. If you are going drilled then a sump is worth it

 

I bought a 90 gallon acrylic corner saltwater tank with a custom built cabinet and includes a 45 gallon sump for the cabinet below. I plan on keeping it a freshwater tank but utilizing it as much as a saltwater setup while still keeping it freshwater. After redoing all the plumbing, I finally, temporarily, set it up for the leak test. With the leak test complete, I poured in 3 gallons of vinegar and fired up the return pump to keep the water column moving. I'm just going to let it cook for a couple of weeks. I think I need to add a couple of powerhead to increase the flow. The two lockline return jets aren't doing much although I did have to restrict the return flow because the water coming into the overflow chamber is pouring in so fast, there's a loud gurgling sound as it's going down the drain to the sump below.
Any thoughts on using a piece of filter floss in the drain opening to even out the flow or should I just keep the return flow restricted? If you have any other ideas, I'd love to hear them.

I've included some photos of the tank and cabinet. The last two pics are of the tank running with vinegar in the water for cleaning. I didn't put the hood on because after the vinegar does it's work and I let it cook for about 2-3 weeks, I'm going to tear it down to finish cleaning it and then buff and polish the scratches out.

 

Well, two weeks ago today I set up the tank and sump and started the cycle with a piece of raw shrimp. During the fill I found three leaks in the plumbing connections, so I had to stop the fill and fixed the leaks, but I finally got it up and running. The coral piece on the far left must have had an air pocket in it, so it just floated to the top of the water column. I let it soak for a couple of days, but it never sank, so I had to take it out and replace it with a piece of rock.
The filter and heater are down below in the sump and the heater is maintaining a constant temp of 77.6 in the tank.

Last weekend, I ran some tests.
Ammonia came out at .25
High PH was 8.2
So, I took out the shrimp and started ghost feeding the tank.
I also added a couple of plants:
2- Amazon Sword
2- Frazeri Anubias

The powerheads were blowing the sand substrate all over the bottom of the tank, so I took out one of the powerheads and through adjusting and re-adjusting the remaining powerhead and return jets direction, I found a good setting and the substrate has settled and stopped drifting around the tank.

This weekend, I ran more tests.
Ammonia was zero but Nitrites were off the charts at 8.8+ so I didn't bother doing a Nitrate test.
PH is 7.2
High PH is 8.2
KH is 6
GH is 12
The Amazon Sword plants are melting, but I found, through research, that these plants are grown out of the water, so the plants are adjusting to their new environment and melting should be expected and I should look for new sprouts in the coming weeks. The Anubias are in great shape. Still no algae as of yet.

Tomorrow, I plan on doing a 20% water change.

I'm going to run tests again, including Nitrates, next weekend and do another 20% water change. Even when water parameters come out normal in the next coming weeks, I'm going to hold off a couple more weeks afterwards, to make sure it remains stable before I add fish or shrimp, but I might put in a couple mystery snails and a few trumpet snails to start stirring up the sand substrate.

Any ideas or advice are, as always, welcome.