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Purple stuff growing on my MJ1200 return pump cord


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Not really sure how else to describe it other than what I have said in my title....


i have no algae in my tank (tiny bit of diatoms on my sandbed and rock... but barely any.... no green hair algae or anything anywhere.... nothing really... my snails keep everything clean and tidy- for example I will go to bed and notice some algae on my glass (a tiny bit) so I will say “oh I’ll get that in the morning” but my snails have it gone but the time I wake up and everything is clean and clear (I still clean the glass a couple times a week anyway)


but i upgraded tk the MJ1200 return pump and as of the last week or so I have noticed like a purple (what I presume to be algae) only on the cord that runs down to the pump... it’s not on any of my other cords but they are all significantly smaller....

i have taken my pump and tubing out during water changes (every second one- twice a month) and cleaned it all in ro/di water... just to keep everything running smoothly....

but I never noticed the purple stuff before?


does this grow on anyone else’s cords? And if so what is it? My son said he wiped it off the other day (not sure if he really did or not) and I noticed it’s back today... just wondering if it’s normal or if it’s going to effect my pump or if something is wrong with the cord??


my phosphates are extremely low- basically undetectable in all test now (showed .02 on UL Hanna repeated a few times even used different sample water)


and my nitrAtes are undetectable as well on all high range and low range tests


ammonia and nitrites are 0


i do a lot larger than I need to when it comes to water changes so that my guess as to why... (I only have 2 O. Clowns and 1 Green Chromis) and I replaced and clean out all the back chambers every water change and I change about 8g of water every Saturday.. I even remove my InTank media basket and clean it and swish around the purigen and chemipure elite in ro di water during the water change to make sure they are all clean... so this purple wire is basically all I have for algae lol

i tried a google search but couldn’t find anything about algae growing on wires and cords like this so that is what is making me worry....


any help or what to try would be great...

i can try to get a picture of it would help anyone...

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Christopher Marks

It sounds like it could be coralline algae, it grows purple, pink, and sometimes white, like a thin calcareous film. Coralline algae can grow on almost anything inside a tank, the walls, rocks, pumps, wires, etc. This is a good example of a tank absolutely covered in coralline algae: 


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Coralline is what it looks like and was my thought but just odd that it would grow in that spot first (I have a bit growing on my rocks)


tank is only a couple months old (cycled for a couple months) and all the equipment was brand new.... it’s a biocube 32... not sure if I mentioned that or not...


Hopefully you can see it from the picture... I’ll do my best but the back of the tank is in a dark spot....

dont mind my water spots back there... haven’t wiped them up from the condensation from when I fed them this morning lol 

if you zoom in on the picture you can see it really good actually (at least I can)



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It may be coralline, but i'll let someone else confirm. 


It doesn't look anything harmful. The tank will grow stuff, regardless of how clean you keep it. It's just nature doing its thing. 


On a side note (in my experience), I wouldn't leave my nitrates at undetectable. I just started my tank a year ago and I always thought that keeping 0 phosphates and 0 nitrates would be good. Unfortunately, I had a dinos outbreak about two months ago and that killed all of my SPS. Dinos can live (and take over) in low PO4/NO3 conditions, but algae cannot. And so the dinos had nothing to compete with and they took over. My LPS/softies are fine, it's more so the SPS that got damaged. So let your nitrates increase to 3-5 ppm, and your phosphates are fine at 0.02. This should allow algae to grow and outcompete other things like dinos. And to "beat" the algae, just get a clean up crew that will eat it.


Not saying this will happen if you keep your PO4/NO3 low. I hear people have beautiful low nutrient tanks.  I'm Just telling you from my experience. It's something I definitely wish I knew before. There's no harm in letting your NO3 get to 3-5 ppm. Many of the most beautiful tanks that i've seen have phosphates and nitrates much higher than this. 

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Ha I didn’t do it intentionally lol (well the nitrAtes were at 20 so I was lowering them) but it’s just from regular water changes... I do a weekly change of around like 5g’s or so (only have 3 little fishes right now and some snails) so I probably don’t need that much and all I am running is InTank tray with floss, purigen and chemipure.... nothing else.... no skimmer, no macro... nothing... I am cautious of not over feeding and such but even my back chambers are clean... a wee bit of sand dust on the bottom but that’s about it... and I’ve been doing my water changes mostly from the back chambers just because I don’t find there’s a lot of circulation going on back there (there probably is and I just can’t see it) but I’ve had nothing to suck out of the DT (I do change a bit of the DT water when I siphon chamber 1) but then I at least know it’s nice fresh water going back into the tank and I have great tank circulation (I have 2 aqamai KPS’) plus just the regular return with the MJ....


but ya I wanted to lower my nitrAtes down from 20 to about 5 and I did 2 weeks of water changes (like in 2 weeks time) and they both dropped to zero....

im sure once I finish my stocking and such it will come back up... and I also am not going to be keeping any sps.... it’s all going to be softies and maybe a few of the hardier LPS... (it’s my sons tank so he looks after it) lol


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