Fluval Flex 32.5 Saltwater (123 Marine) - Back to Reefkeeping

[JReef3]

Following, currently putting together my rocks

Nice, that’s a really fun part. Hope you’re taking pics and considering a build thread.

Love the shape of the fluval tanks. Rockwork looks great! I built a fluval 15 gallon freshwater tank for my daughter she loves it.

Yeah, I’m really liking the shape too. Thanks on the rockwork, I appreciate it! Funny you mention doing a 15 for your daughter, I’m thinking of doing the same for my kids.

 

[Shanel]

This is the 15 gal I

did for my daughter.

 

[JReef3]

This is the 15 gal I did for my daughter.

Great looking tank, I’m sure she’s quite happy with it! Thanks for sharing.

 

[JReef3]

Cycle Update:
Today completed day 10 of the tank’s cycle. As I mentioned before, I haven’t cycled a tank in years and have never done a fishless cycle before. Just 3 days ago, wrapping up day 7, I felt that things were on track as I was getting zero(ish) test results for ammonia (thanks API for the ambiguity) and nitrites were present. From what I’ve read, the bacteria that process nitrites can be a bit slower to come to the party than those that process ammonia so I wasn’t too worried about it but nitrites seem not to have budged since showing up on day 4. I know they’re not supposed to be harmful to a saltwater tank in moderation but I was still expecting to see the sequential spike and processing of ammonia > nitrite > nitrate and the API tests have not reflected this. I’ve been searching R2R endlessly and some would call this a stalled cycle, others would say the API test is giving false readings, and still others would say to give it time and be patient.

For being such a common event as we’ve all done it, some numerous times, cycling a tank seems surprisingly inconsistent to me. For some it follows an obvious transition from one step to the next and for others it seemingly “stalls” at one point or another. People talk about the presence of nitrites causing false nitrate readings in testing as well. It’s amazing, as illustrated by the number of threads on the subject, how many concerns arise over something that theoretically should be relatively predictable and easily tracked.

It seems that many people these days consider a tank cycled if it can process ammonia to nitrite which my tanks seems to have done. To verify this, after documenting the day 10 daily test results, I went ahead and dosed the tank with 20 drops of ammonium chloride which was just enough to bump the API test results clearly from yellow/0ppm (baseline) to light green/0.25ppm. From what I understand, if in 24 hours the ammonia is back down to 0ppm, that should be a decent indication that the tank is adequately cycled. Per a recommendation in another thread I was reading, I took a photo of the day 10 ammonia test result prior to dosing ammonium chloride, a second photo after dosing to document the elevated ammonia level, and tomorrow I’ll take a third photo to see if the ammonia has been processed and is back down to zero/baseline. If it is, I guess it’ll be time for a water change and then a few clownfish.

Here are the day 4 test results where ammonia is still clearly present and nitrites have shown up as well. Ammonia read higher than the expected 2ppm based on the amount dosed, perhaps due to a miscalculation in the amount of water displaced by rock and sand or due to ammonia present in the rock and sand. The nitrates may or may not be a false positive based on the presence of nitrite I suppose.

And here are the day 10 test results prior to dosing additional ammonium chloride. Ammonia seems to be absent and nitrates remain roughly the same. I’m not sure what to make of the nitrate reading again not knowing if it is a false positive due to the presence of nitrites. The nitrate testing seems fluctuate between gold and red depending on the day.

And finally, here is the before dosing 20 drops of ammonium chloride (left) and after dosing (right). The camera makes them look darker than they actually are but no matter the color, I’m just looking for a return to baseline. I’ll be very interested to see what it looks like tomorrow morning and then tomorrow evening 24 hours after dosing.

If anyone has thoughts, theories, tips, or any other input on this cycle, please do chime in; I’m really fascinated by this process.

 

[JReef3]

Cycle Update:
Today is day 11 of the cycle. Yesterday evening I dosed the tank with 20 drops of ammonium chloride to increase ammonia to the next higher color on the API test chart so that I could see if nitrifying bacteria are sufficiently present to convert it to nitrite in a day. This morning, 16 hours after dosing, the ammonia has gone down back to baseline.

Here is a series of 3 photos taken before dosing, right after dosing, and 16 hours later.

While it appears the ammonia is being converted well enough, nitrites were still present at or above 2.0ppm per the API test. I realize this is a safe level for saltwater aquariums but I’m still confused as to why it’s reading at this level. Perhaps the bacteria that convert nitrites to nitrates are still colonizing? Since I questioned the API test kit, I tested clean/new saltwater and API reflected 0.0ppm nitrite so the test seems to be at least somewhat reliable. I’m also still showing nitrates but I assume this is a false positive because nitrites are still present.

Because ammonia has been confirmed to be converting to nitrite, and since nitrites seem not to be changing, I went ahead with a 50% water change and took daily readings.

Here are day 11 test results:

Cycle Update/Edit (Day 14):
For anyone following along with my tank's cycle, rather than create another post, I'll just edit and add here. A day after adding fish, I'm at day 14 of the cycle. I tested today and ammonia is still at zero, nitrites have finally dropped off and are barely detectible reading at 0.25ppm, and nitrates are around 15ppm.

Cycle Update/Edit (Day 15):
This will be my last cycle update. I tested parameters for the cycle today and ammonia remains at zero, nitrite is now down to zero, and nitrates are present at about 15ppm. The official cycle seems to be complete. I now have the lights on to enjoy the fish but I’m keeping them very low and for only a short time each night for now to try to avoid as much of the ugly stage as I can while the tank matures a bit and then I plan to eventually increase duration and intensity of lighting over time once the tank seems stable and ready for some corals.

 

[JReef3]

First Creatures:
With the cycle complete, at least to the point where it has been confirmed to be converting ammonia to nitrite, and with a water change done, I decided it was a good time to add a few hardy fish. I went with clownfish since they’re bright, active, kids like them, and they can form cool relationships with other clowns and anemones. I really wanted a bonded pair of clowns which you can buy online but since they cost quite a bit more and you don’t get to pick the exact ones in most cases, I watched a few YouTube videos and decided to try getting two clowns to pair myself. I went to my LFS who had over a dozen types of designer clowns and I picked up a juvenile Misbar Clown and a smaller juvenile Wide Bar Gladiator Clown. I also picked up one Nassarius snail to kick off the CUC since my kids are obsessed with the idea of a “zombie snail” that comes crawling out of the ground. ;Walkingdead

With help from the kids, we named them. I’d like to introduce Missy the Mis Bar, Spartacus the Wide Bar Gladiator, and Sandy the snail.

 

[CLFishies]

History:
After more than 5 years tankless, I decided to get back into reefkeeping. About 10 years ago when my daughter was on the way, I decided to downsize from a 90gal mixed reef with a 30gal sump/fuge to a 28gal JBJ LED Nano Cube as I knew my free time would be limited. Fast-forward 5 years and the Nano Cube cracked a few days after we moved to a new house. At that point I packed my LR from the Nano in a 5gal bucket, stuck it in the shed, and gave away the remaining fish/corals to a good home. Fast-forward 5 more years and here we are. I decided to stick with the 30ish gallon AOI category like my JBJ Nano was since, now having 2 kids, I appreciate the low-maintenance aspect of it. After quite a bit of searching here and googling around, I decided to go with either the Fluval Flex 32.5 or a BioCube 32 as both are the size I’m looking for, both have decent LED lighting, and both have lids which I find to be a must with my kids to avoid stuff flying into the tank. I ended up going with the Flex for a change of pace since I’ve done a cube before and because I like the longer/wider footprint with the same volume for the slightly more spread out aquascaping possibilities.

The Big Purchase:
Perhaps due to the pandemic, I found only 3 places online that carried the Flex 32.5 Saltwater but in a stroke of luck, I found one on the shelf at my LFS for the same price as the least expensive one online so I picked it up.

The Plan:
- Top Fin aquarium stand with a modified top to accommodate the wider footprint of the Flex
- 24lbs of natural Fiji LR (now dead as it’s been in a bucket for the past 5 years)
- 10lbs of dry rock from the LFS
- 40lbs CaribSea Fiji Pink live sand
- Livestock will consist of a mixed reef and community fish hopefully including a BSJF or a Goby/pistol shrimp pair
- Equipment will start off stock to give Fluval’s design a chance with upgrades likely to follow including a higher output return pump and InTank media baskets. I have an Inkbird heater/fan controller on the way and will cycle the tank with my 2 old Eheim Jager 50W heaters from the Nano with plans to replace them with 2 new 75W or perhaps some Fluvals. For circulation, I will start off the Hydor Koralia Nano I have from my old NanoCube.

Current Situation:
I find myself really excited to be getting back into such a great hobby. I didn’t realize how much I missed it until I considered starting back up. I’m now, as patiently as I can, going full speed gathering everything I need to get this show on the road. I really appreciate everyone on this forum who has already shared so much of their knowledge and experience with me and I look forward to learning and sharing with everyone as all of our reefs progress.

Prior Tanks:
I’ll leave this first post with a few photos of my old 90 and my 28 to show where I’ve been and posts to follow will have photos of the new Flex 32.5 to show where I’m headed. Thanks to everyone who has lasted through my long-winded intro.

Here’s the old 90gal I had about 10 years back.

And here is my JBJ NanoCube, my last tank before I took a break from reefkeeping 5 years ago.

Sand & Rock:
I decided to go with live sand since I like the idea of it coming with some beneficial bacteria and I figured that the more sources of bacteria the tank had, the more diverse and successful it would hopefully be. I debated over sand size as I wanted something fine enough to be sifted by a goby but coarse enough for a pistol shrimp or a Bluespot Jawfish to dig and maintain a burrow. I also didn’t want the substrate to be so fine it would blow around and not so coarse it would catch detritus. I ended up going with CaribSea Fiji Pink and ordered 40lbs as I wanted a deep enough sand bed to accommodate a goby/pistol shrimp pair and a Jawfish. The 40lbs worked out to somewhere between 1 - 1.5 inches deep so I may need to create a deeper sand lagoon for a Jawfish. Once I got it in the tank, I found it to be a little more fine than I thought it would be but but I like it. Also, like many people say, you really don’t notice the pink specks in it at all; it just looks like clean sand.

For rock, when my NanoCube cracked 5 years back, I took the Fiji and Tonga live rock and put it in a 5gal bucket full of saltwater and threw it in the shed where it sat in the dark, without circulation, and at temperatures from about 30-100F. When I opened the bucket 5 years later everything should have been dead but there seemed to be some polyps, something that looks like tunicates, and a bit of some sort of red macro algae. I brushed them off, hosed them off, RO/DI dipped them, and then threw them in heated, circulating saltwater for a week. By the end of the week I checked them out and there were no signs of anything decaying so I called them good. I wanted a bit more rock for the aquascape so I also went to the LFS and picked up a few dry rocks as well. Since I was at the LFS picking up dry rock, I also picked up a half pound of LR rubble for a bit more bacterial diversity and to seed coraline algae.

This is the Fiji and Tonga rock from the 5gal bucket circulating in a tub after being cleaned off.

Below was right after adding the sand and rock. The CaribSea comes with a packet of Bio-Magnet clarifier to help with the cloudy water so I threw in to see how well it would work.

The water clarifier worked pretty well. Within hours the aquascape was visible and by the next morning it was totally clear. (Keeping the lights off until it is cycled to minimize algae.)

Looks good. I downsized from a 90 gal. in March. I do miss the big tank but the 32.5 is easier to take care of. I did do a few upgrades, new mounts for the light, new pump, and ditched the lid.

 

[JReef3]

Looks good. I downsized from a 90 gal. in March. I do miss the big tank but the 32.5 is easier to take care of. I did do a few upgrades, new mounts for the light, new pump, and ditched the lid.

Thanks, it’s a start. I miss the big tank and options it offers too but like you said, the Flex is quite a bit less maintenance. You tank looks great! What return and circulation pumps did you go with?

 

[Reydin]

Just my two cents but I'd ditch the API test kit and go with something that is more accurate. API was showing that I had 0 nitrates and phosphates but in actuality I had 47 ppm nitrates and 0.46 phosphates.

 

[JReef3]

Just my two cents but I'd ditch the API test kit and go with something that is more accurate. API was showing that I had 0 nitrates and phosphates but in actuality I had 47 ppm nitrates and 0.46 phosphates.

I couldn't agree more. It was an affordable test kit bought just to track the cycling of the tank and, in hindsight, it worked well enough in my case even though I questioned it at times. It was able to clearly demonstrate ammonia added one day and processed out the next which is ultimately what I needed to see. I've read some horror stories about wildly inaccurate API tests like your experience and I actually experienced the same a few times with results that were totally unexpected so I had to go back, clean the vials, re-read instructions, and test again. That said, I'm looking into Hanna checkers, Red Sea, and Salifert for water parameters I'll be testing regularly over the life of the tank.

 

[LadyMac]

This is lovely! I’ve been eyeing those flex tanks for some time. How do you like the light? I have their freshwater aquasky, and it’s not bad. I’ve heard the reef version and the planted 2.0 were both phenomenal

 

[JReef3]

This is lovely! I’ve been eyeing those flex tanks for some time. How do you like the light? I have their freshwater aquasky, and it’s not bad. I’ve heard the reef version and the planted 2.0 were both phenomenal

Thank you, I really enjoy it. I can't speak to the lighting as far as coral growth because I have not yet introduced any corals, I'm waiting for the tank to mature a bit more. I have read in numerous threads that it is very capable of supporting softies, LPS, and even some SPS corals with just the fixture that it comes with. The tank also comes with an extra set of brackets so you can add a second light fixture which Fluval offers separately if you wanted to do an SPS dominant tank for instance. From my experience with the light for fish only which is what I have for now, it offers very good controllability through the app to get whatever color and intensity you like.

 

[Reydin]

I couldn't agree more. It was an affordable test kit bought just to track the cycling of the tank and, in hindsight, it worked well enough in my case even though I questioned it at times. It was able to clearly demonstrate ammonia added one day and processed out the next which is ultimately what I needed to see. I've read some horror stories about wildly inaccurate API tests like your experience and I actually experienced the same a few times with results that were totally unexpected so I had to go back, clean the vials, re-read instructions, and test again. That said, I'm looking into Hanna checkers, Red Sea, and Salifert for water parameters I'll be testing regularly over the life of the tank.

I bought the Hanna checker and verified the results. In the end I ended up killing off several LPS because of the API kit and the inaccuracy of it.

 

[Reydin]

Also, I recommend the intank media baskets and their bulk filter that you can cut to fit. The stock filters are awful. There are dead spots where detritus can build up in the back filter chambers that isn’t caught by the filter. I change the filters about every 3 to 4 days and also use Chemipure elite. It has help to reduce phosphates and nitrates.

 

[JReef3]

I bought the Hanna checker and verified the results. In the end I ended up killing off several LPS because of the API kit and the inaccuracy of it.

Hanna is definitely more accurate than API from what I've read. I've got a Hanna Phosphate checker on the way. Looking forward to giving it a try.

Also, I recommend the intank media baskets and their bulk filter that you can cut to fit. The stock filters are awful. There are dead spots where detritus can build up in the back filter chambers that isn’t caught by the filter. I change the filters about every 3 to 4 days and also use Chemipure elite. It has help to reduce phosphates and nitrates.

The InTank seem to be really popular upgrades. I've got a pair of them as well but haven't gotten around to installing them just yet. Perhaps this weekend.

 

[JReef3]

Light Adjustment:
I noticed that I had quite a few shadows in the tank caused by the upper rocks in my aquascape. The stock hood comes with mounting holes to have a single light in the center or you can buy a second fixture and move the single/original one slightly forward of center and the second/new one slight to the rear of center. I found that since the sump area on the Flex 32.5 sticks out several inches from the back into the display tank, the rockwork is nearly in the center of the tank as well so the single light fixture that comes mounted in the center of the hood ends up directly over the rockwork casting shadows on the lower rockwork facing the front of the tank.

While I currently have just the one light fixture and I don’t necessarily plan to get a second unless I decide to keep certain SPS, an anemone, claims or other higher-light livestock down the road, I decided to move the single fixture to the forward position to reduce the shadows. It was very easy to move the light fixture forward by just removing the two brackets on the ends of the fixture held on by 4 screws and then I repositioned it in the forward of center space. Since I didn’t take a before photo with my current light settings and since aquariums are difficult to photograph with a true representation of lighting and shadows so you’ll have to take my word that the shadows have been noticeably reduced by this move.

Here is the single fixture moved to the forward position.

The brackets are very easy to unscrew and move with just 2 screws on each bracket.

The sump sticks out so the rocks are nearly in the center just below the stock fixture position.

The photo makes the front rockwork look like it is still in shadows but it’s noticeably better and now has slightly more direct light which should easily support softies and LPS in most areas.

 

[carolina rojas]

Looks good. I downsized from a 90 gal. in March. I do miss the big tank but the 32.5 is easier to take care of. I did do a few upgrades, new mounts for the light, new pump, and ditched the lid.

Hi!!!
I want to know, if you can please let me know jeje.. what kind of hang racket you have on the light of your fuval 32.5?

 

[JReef3]

Goby & Pistol Shrimp Pairing:
I’ve always loved keeping a goby and pistol shrimp pair. For the Fluval Flex, I decided to stick with a smaller pistol shrimp so I went with a Randall’s/Candy Cane. For the goby, I decided on a Yellow Watchman Goby (YWG) as I like their color and grumpy face. I really wanted them together so I was hoping to find them already paired but for whatever reason, I was having a hard time finding a Randall’s by itself let alone paired with a YWG. I ended up making a several hour trip around to the 5 LFS within an hour of me and was fortunate to find a healthy YWG and one Randall’s pistol shrimp who, while healthy, was missing one small detail, his pistol. I had read that they could lose their claw when molting and that it would eventually grow back so I went ahead and got him.

I really wanted them to be front and center in the tank rather than picking out their own spot in a dark corner in the back where I’d never see them. I had already planned on adding them when I was aquascaping so I had put a rock with a natural hollow spot toward the bottom facing forward when doing the rockwork. Prior to making the weekend LFS trip, I decided to sweeten the deal for them by pulling out a bit of sand at that opening and adding a few extra rocks at the front of the cave and a bit of crushed coral and shells that the shrimp could use to reinforce their burrow.

Once they were ready to go into the tank, I put them in a specimen container and then poured them into a water bottle so I could control their entry into the tank and specifically, into the cave I made for them. Here’s a video of how that went.

After a few days of not seeing them, I discovered that the extra rocks I had added to the front of the cave were acting as a patio of sorts keeping them out of sight while they were actually sticking out of the smaller, more natural hole in the main rock I had originally intended them to live under. I removed the extra rocks from the front and ended up with this.

 

[JReef3]

InTank Media Baskets:
It seems that replacing the stock media sponges is a universally agreed upon upgrade for the Fluval Flex. The stock sponge does not allow for control of flow directly through the media in the sponge cutouts and the sponge is not easily cleaned which can lead to trapped detritus and less than desirable water parameters. I looked into options and found that the InTank Media Baskets are a very popular choice and that another possibility was the 3Deep media basket.

https://intankaquatics.com/intank-media-basket-for-fluval-flex-32-5-fluval-flex-123l/

https://www.3deep.co.uk/product-page/fluval-flex-123l-media-basket-pair

I ended up choosing the InTank option as they seem to have a good track record and the baskets and filter floss seemed more easily available either direct from InTank or from Amazon. It seems that InTank didn’t use to include flow directors (plastic ruler shaped pieces) that ensure a tight fit and proper flow when they first released the baskets for the Flex but have since began shipping with the directors included.

Here are the old media sponges and you can see how porous they are and how easily they trap detritus. The detritus built up on them is from the past several weeks during the cycling of the tank and then a few weeks of feeding a few small fish. You can also see the detritus that was building up on the louvers of the filter chamber the water would flow through with the stock filter sponge design.

Here are the new InTank Media baskets and you can see the black plastic ruler looking things which are the flow directors that came included.

Here you can see the placement of the flow director, it creates a fairly tight fit for the basket forcing the water up and over the top of the basket into the filter floss and then down through the various media in the chambers of the basket rather than allowing it to flow around the sides of the basket.

I ended up buying a value pack of the InTank filter floss on Amazon and just cut out a bunch of pieces so moving forward, I will be able to easily change out the filter floss perhaps once a week along with water changes.

You can see that the flow with the new InTank baskets in place is much more controlled and water is clearly directed right through the filter floss. I intentionally stirred up all the detritus I could find and cleaned a film on the silicone joints of the tank that formed creating quite a bit crud floating around in the tank to see how well the baskets would filter out the detritus and they really did clean up the water quite quickly.

For now, I only have filter floss on the top and the media chambers are empty. I’ve been reading about the numerous options for media and I’ll have to figure out what will be most beneficial for this tank. I’ll also be installing an upgraded return pump shortly to increase flow through the sump/filter area in effort to get better surface skimming.

 

[JReef3]

Return Pump Upgrade:
I think the stock Fluval/Hagen pump provides adequate flow through the Flex sump for filter pad and media purposes, but I wanted stronger flow through my sump mostly to improve surface skimming. It seems that the Sicce Syncra Silent 1.5 was hands down the most popular upgrade/replacement pump for the Flex and it’s rated well on BRS and Amazon so I thought I’d give it a shot.

When pulling out the old pump I found that it has a sponge surrounding the intake that had quite a bit of sludge building up on it so I was glad to see that go. The Syncra 1.5 does not have a sponge inside the intake like the stock one and is physically a slightly smaller pump. The Syncra comes with two barbed fittings but you only need one if using it in the sump, I believe the other can be added if you’re using it as an in-line pump. The barbed fittings it comes with are the same size as the stock pump so it’s a direct fit replacement.

Here’s the stock pump and the build up of sludge on the sponge inside of it after 1.5 months.

Here is a comparison between the two pumps.

I had a bit more faith in the new pump than I should have as I didn’t bother to test it and just installed in in the sump, hooked it up to the return, routed the power cord, and plugged it in. Unfortunately, like some of those on Amazon who left negative reviews of it, mine had quite vibration noise to it. My first thought when I hear others having this sort of issue is that they didn’t put the suction cup/vibration dampening feet on right or have the pump housing or power cord touching a wall or something of that nature but that wasn’t the case. I pulled the pump, held it in the middle of the DT (display tank), and turned it back on and it continued to make the same noise just suspended in the water. I pulled it apart, inspected it, and reassembled it with the same result. After some searching, it seems some say that it has to break in and quiets down after a few days so that’s where I’m at. I’ve reinstalled it in the sump area and have it up and running/humming. We’ll see if it settles down or if I need to get a replacement from Amazon or perhaps consider a different pump.

On the positive side, the stock pump puts out 214GPH and the Syncra puts out 357 so I can definitely see an increase in flow rate through the sump intake grills and then through the filter floss into the InTank baskets. I have the outlets of the return aimed upward a bit so the surface of the water in the DT gets agitated more to reduce the film of organics on the surface and to improve gas exchange.

I took some photos along the way to show the size difference between the two pumps.