How to Troubleshoot a Problem Saltwater Tank

Between watching fish die and your money go down the toilet, a problem tank is a real drag.

The good news is that any problem tank can be fixed with the right approach. In this episode of Mr. Saltwater Tank TV, I show you how I troubleshoot problem tanks so that you don’t have to wonder what to do with a tank that has issues.
P.S. Don’t miss the link for the downloadable flowchart!

Links in this video:

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Comments for this article (17)

  • David says:

    Hello that’s what I did with my nitrate problem, mine was 100ppm, took 10 fish out , got new deltech tc2060. And move rocks around to help flow. Taking months to fight this problem but slowly getting there, nitrate now about 10 to 15 ppm, do you know when hanna checker for nitrate is out Mark .

  • Derek says:

    Thanks Mark! My fish are happy now and they can move around without getting all scraped up in my tight rock work.

    You’re the man!

  • Dan says:

    i felt just like him after my tank crash… its a huge shock to try so hard to succeed then fail due to something beyond our control or knowledge. especially the $ investment. perfectionism will be the death of me

  • Kovy says:

    Hey, Dereks tank in my opinion needs more flow. He should look into some powerheads, or if he could afford it, a wavebox. Detritus and other organics in the water wont be able to settle as long there is a random/chaotic movement in the tank.

  • Kovy…the wavebox went in this week!

    Also…random/chaotic movement can help prevent detritus build up, but closed rock work can create dead spaces where no flow can get to. The two (flow and open rock work) go hand in hand.

  • Kovy says:

    Wow Mark, thats impressive that you can get a guy to spend money like that. Also have you spoken to him about his skimmer? You mentioning in the video that the skimmer was too small. I know from experience that skimmers are one of the best things you can do for your tanks, and not only should you own a skimmer capable of handling your entire system, but going even larger will definitely make a difference. Like you say, “Go plus 1”.

  • He already upgraded the skimmer and I agree about skimmers. They are worth their weight in gold.

  • Marc M says:

    I have a FOWLR system that houses 3 large angels and 7 large tangs including a unicorn and my only nitrate control is my sulfur reactor. I run this 24/7 and my nitrates are ZERO. Waterchanges don’t work and neither do refugiums unless you have one that is 300 gallons filled with caulerpa.


  • wesleyforbes says:

    Nice video! I really like seeing the beginning and end of a problem. I had the same exact problem except throw in a lot of hair algae! I ended up taking my rock out reaquascaping, adding new skimmed (swc 160), two phosban reactors for carbon and phosphate removed, and adding cheato to the refugium. A lot of work, money, and patience but all worth it, nitrates between 0 and 0.02 no hair algae and no fish deaths! ( Knock on wood).

  • Daragh says:

    Hi Mark
    I would love to rescape my tank but I’m worried about moving the rock in one go.
    Do you find that this will cause stress with the fish and corals.
    I recently lost an acropora and don’t want to lose any more. All my parameters are good except my calc and kh ( they are running high but water changes are bringing them down ).

  • Robert says:

    Hi Mark, I enjoyed the video. I would love it if you did a segment on algae. I have a 110 gal. tank and I cant seem to get my algae (green hair) problem under control. I have order a phosphate reactor and its on the way. My readings for phosphate are zero atm. I dont know if its my test kit (I am going to get another one to check) or im getting a false readying because of the algae (its not every where but on about 30% of my rocks). Can their be any other cause of algae besides high phosphates? If it is the phosphates when I get it under control will the algae go away or will I have to manually clean the algae off, change rocks, etc….. help!

  • Dennis says:

    Yeah definatly make a algae problem flow chart mark.
    that would be a massive hit on youtube for you

  • Josh Rodriguez says:

    Thanks for this video! I have a 12 gallon nano cube and my water is murky after 3 weeks of the set up. I have one clown who poops a lot even after i reduced his feedings to 1 small feeding a day. I’ll re arrange my rocks and re-direct the water flow. And i placed an order from thanks to your video and plug in about them. Fish is fine, and so are my 5 hermit crabs and 3 turbo snails (i think their turbo) And with my order, my sand should be sifted thanks to the Cerith snails. I’ve also carbon dosed my tank and the water is still a bit murky. But thanks to your VIDEOS my tank will look a lot better in a week or so. Hopefully!

  • Stacey says:

    The link to tank problems takes me to an econmerce selling website. Uh?

  • Stacey..the link to the checkers should take you to an ecommerce website. The others direct to pages on my site. Were you seeing something different?

  • ryan says:

    Mark, do you offer one on one advice? I have a few problems with my tank and really having a very hard time keeping any coral. Thank you in advance!

  • adrian says:

    I have a red sea reef tank 525liters has been running for ten weeks it was ok I did a water change , and my water started to go green , so was advised to turn lights off for three days, to see if that helped also added carbon but it is not getting any better do you have any advice on what I can do.

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