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Fluval Megaflex - Seeking Stocking and Aquascaping Advice

Brave Ulysses

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I've had a 32.5 G Fluval MegaFlex for almost 3 years now but I just have never really been happy with the aquascaping in it and have had poor results with live plants, bearded algae growth, and being able to keep some fish long term.
- Currently have 7 panda corydoras (they bred a few months ago apparently and went from 5 to 7)
- Two (now pretty large) yo-yo loaches. 
- One bristle nose catfish 
All of these fish have really been in the tank since the start.. 
Over the past 3 years I have tried: 
school of tiber barbs (they did well for 1.5 years... and then one got sick... and then within 2 weeks all of them had died). 
pearl gourami - only lasted a few months and never seemed happy. 
Blue Ram Cichlids - have tried twice..... only lasted a few months
Ruby Clown Cichlid / Bolivian Cichlid - only lasted a few months. 
The biggest challenge seems to be my water.... we are on a spring/well/mountain runoff system and the pH of the water seems high. 7.8-8.2. I knew this going in and added a lot of driftwood, but it didn't seem to make much difference. I also added CO2 for a while and it didn't lower the pH much, helped the plants a little bit, but seemed to help the algae more than anything. The last time I tried the Ruby Clown Cichlids I tried very hard to buffer the water with Seachem's Neutral Regulator.... initially it seemed promising, but when the Ruby Clown Cichlids died I abandoned that and let it return to its natural pH which has not seemed to be a negative for the corydoras, bristle nose place, and yo yo loaches.
A few weeks ago I had a really bad outbreak of bearded algae (not the first time), but I've cleaned the tank more frequently, and moved the tank location out of afternoon sunlight and it's getting better. 
  1. I have medium size round gravel and black sand in it. Should I add some type of substrate for the live plants?
2. What changes could make the aquascape look better? Should I add CO2 again for live plants?
3. What fish would you recommend adding given the above? I'd like to add some much more lively and fun fish to make the tank a bit more interesting. I'm currently torn between just going for a basic community tank with a bunch of tetras and smaller community fish, or trying to see if African Cichlids could work given the pH, or maybe even trying a Convict cichlid with some barbs. I really wish I could get either the Blue RAM or Ruby Clown cichlids to thrive in the tank as I really like them and they are readily available here, but I feel bad at this point after multiple failures.



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Hi! Saw nobody had answered you yet so I have a few insights. Welcome to the forum! 

I would ask you personally first- ask yourself- do you get bored easily with your tank? I know a lot of hobbyists that just like changing it up constantly. If that is you, this might just be your pattern in the hobby, maybe changing things up keep you interested. However, if it is just overall dissatisfaction with what you have had so far I would consider these points.

You do have high pH so if you don't want to be become a water chemist and mess with that constantly and put your fish in a wobbly environment occassionally (which causes stress and illness) then stick with fish that are high pH tolerant. I think you have good options there. IMO the largest of the Flexes isn't the best tank for most cichlid types because generally you get fewer fish and less action. You did express some interest in having a more "exciting" tank. I think a community tank is the way to go. Personally I think a combination of Molly, Swordtails, Platies and Guppies make for an exciting tank. If you don't want reproduction you can go with small combinations of males that are generally pretty and never ending movement. 

I think you can also consider one of a few of our favorites here that might be able to tolerate your parameters: Bolivian Ram. They are a lot less picky about pH than their Blue Ram brothers and while not as pretty according to some (I disagree) they are FULL of lovely personality, are a great centerpiece and would occupy the bottom half of the tank. I would check your area for Bolivians kept in similar parameters. 

As far as plants, yes, get yourself some actual plant substrate this will definitely help you- even if it's just gravel. Plants that need their roots covered will not benefit by being in sand as it doesn't allow nutrients to the plant- then they suffer. OR, switch it up to rhizome plants only (Anubias, Java Fern) which don't require planting.

Edited by xXInkedPhoenixX
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Thanks for the response.  

1.  Definitely not someone who gets bored easily with the tank.  Not sure if my post gave an impression otherwise.  I've had this tank for 3 years.... all the fish in it right now were there from the beginning and it looks basically the same.  I've just been unsuccessful adding more fish to it, but even when I have, I've been very patient, and I've waited several months to try again.  

2.  I've been concerned that most community fish wont do well in the higher pH and with my now very large yo yo loaches.   The worst scenario for me is getting a school of fish, and then only have 1 or 2 remain for an extended period of time, because then I feel bad about the ones that didnt make it, and limited by the ones remaining.  That's what happened with the barbs.... they all did well for a few months, then one passed, then others, but there was one green tiger barb that lived for 2+ years.  

3.  I've tried Bolivian Rams (ruby clown cichlid) and the pair seemed to be doing really well...... and then they both died within a week a few months into having them.   It sucked and I still don't understand what went wrong.  I test the water parameters religiously and do weekly water changes.   It just seems like there's something else in my water that causes problems for many fish that should be fine in my water but ultimately are not, and I can't figure it out.   Maybe hardness?  

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Bummer! Yes I agree with @Galabar, when you test next, post your results here and let us know what they are (or post your last ones). Barring anything crazy there it could be a water issue but I wonder about that until we see further. How often do you clean the filtering on your tank? I find that I have hard luck with closed systems like the Flexes- I've had one, and I had mysterious deaths as well- so I've given up entirely on that style of tank. 

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Im also pretty new.  I can share insights about my learning from youtube and other people and my little experience. I don't know if Fluvals are really paludarium friendly but you can always try, the shape is pretty idea for it. Unless you plan to stock the tank with bigger fish such as Chiclids you should try a community. Have fish that are active in all water columns. If you are interested in breeding (like me), turn it into a project with a big colony of shrimp. I also recommend to use only NATURAL decor, you should avoid artificial stuff as much as possible in my (debatable) opinion. I also think testing the water and finding perfect parameters before doing ANYTHING would be ideal, if you decide to add fish after you think the time is right, monitor water parameters closely and try to find the sweet spot where all fish are happy. 


Fish recommendations

-a school of bottom dwellers such as Otocinclus or Corydora 

-a school of vibrant fish like Celestial Pearl Daino, or maybe Tetra? or try a betta Sorority (if you think your experienced enough) 

-Nano fish like Ricefish or Rasbora(personally I think these are great for big tanks because you can fit more and it looks more active)

-A big colony of shrimp.


Plantwise although, i'd say you should try bigger plants in the background and smaller plants and rock accents in the front for a more aesthetically pleasing view. Nothin in particular comes to mind.



On 11/15/2023 at 1:35 PM, Kaiju said:


ideal, sorry.

Edited by Kaiju
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