PVC may not be aquarium safe

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Dovii
MFK Member
Aug 4, 2008
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So I've been doing some research lately into the different kinds of plastics that we use in our aquarium, and I found some quite damning things about a few of them, particularly PVC. Polyvinyl chloride, or PVC, is only rated as safe for humans when used with cold water; when exposed to warm water, it can leach out some nasty stuff, and as it erodes (say... from acidic water or from water movement), it breaks down into microplastics. You may have heard that word in the news a lot lately, because it's been turning up in frightening quantities in marine life. Microplastics are to plastic what sand and silt are to rocks... over time, water movement breaks down plastic into tiny little particles, which bioaccumulate in the ecosystem.

Now, this came at a very interesting time in my life. One of the oldest animals I have, and by far the longest I have ever had a fish, is my pike cichlid. She's an adult female belly crawler, and she lives alone in a twenty long. If you've kept belly crawlers before, you're familiar with their moray eel-like behavior of staking out a hiding spot and lurking with only their heads protruding, always watching the surface (they are insect eaters, so their eyes are up-turned, keeping an eye out for any unfortunate fallers-in). So, PVC pipes seemed like the perfect furniture for her. For years, she had two long PVC pipes in her tank, and she used them all the time. Quite interesting to watch her slither around, winding in and out of them. I suspect she even moved them around at night. But over the last few months, I started noticing this weird white stuff starting to accumulate near the surface of the tank. It's light enough to float on the surface, and it seems to re-appear even after being skimmed off. It's quite different than the organic matter that forms in any bioactive aquarium. I've never seen anything like it before.

It was quite a mystery until one day I decided to thoroughly clean out her enclosure, and after handling her PVC hides, I had little white flakes all over my hands. I started to put the pieces together.

Like most South American river fish, belly crawlers are most comfortable in a warm tank with heavy water flow and acidic water rich in tannins. I do my best to provide that with a driftwood pile. What I surmise is that, over time, the acidity of the water combined with the water movement, over a period of years, lead to the erosion of the PVC; hence the little white flakes on the surface of my tank.

Needless to say, I will not be putting PVC pipes in any of my aquariums from here on out.


I know this will sound far-fetched to some, and some people probably won't believe me. But the maintaining of animals in captivity is an ever-changing endeavor, and we learn new things every day. If you don't believe me, ask someone who was keeping fish in the seventies what it was like. There is always progression, and the hobby is always changing. I just thought I'd share my experience because I know a lot of people use PVC in their aquariums.

I'm interested to hear what you guys think about this.
 
Very interesting. Been keeping some PVC pipes for over 8 years and never experienced anything harmful. I even scrub them from time to time due to algae and nothing comes off. I have maybe 6 for my fry all various sizes.

If you say PVC is not safe but why is that most of the bigger aquariums are all plumbed with PVC. Its always running through the aquarium water. Not saying your wrong but I'm saying I know some tanks with the same PVC plumbing for over 20 years... I can say maybe 40-50 percent of people on here have some sort of PVC plumbing to PVC pipes in the tank for caves.

Again not saying your wrong but I disagree completely. Its been in the hobby for way too long my fathers plumbing for his koi pond is 25 years plus....
 
I was under the impression that PVC pipe was fine for aquarium use since we don't keep our tanks warm enough to cause any changes in the PVC.

Your comment on seeing white stuff floating on the water surface reminds me of what happens when the anode tube in a hot water tank has started to disintegrate. Have you noticed a reduced water flow in your faucet aerators or shower head?
 
PVC is rated as base rating of 73F and goes up to 140 F. The ratings are based on pressure and reduced capacity relative to PSI, not based upon leaching. In other words, PVC will potentially fail as the temperature goes up. (Nothing unusual in that....all materials tend to fail as temperature increases.)

I have read that PVC doesn't start to leach until it nears 140 degrees so there would seem to be no issue for fish.

http://www.todayshomeowner.com/are-plastic-water-pipes-safe/

According to this link, the issue is related to PVC made prior to 1977. Just FYI.
 
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I have pvc pieces in my aquariums for over 25 years. Never a problem. Only thing that would come off of them if I ever did scrub them would be the bio film or any algae that may be growing on them. Next you'll be telling us the plastic in the filters that have been running for 30+ years is no good. LOL!
 
I think this is along the same line as the issue with BPA in food/water containers. While research shows a link between BPA and certain health implications, its just not a definitive conclusion as to whether it really is detrimental to a persons' health or not.....but suspect
 
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