PVC Tubing

ReefPig · Jul 13, 2020

I was having issues with air bubbles in my silicone dosing tubes and I was advised the issue could be resolved by replacing with the GHL PVC tubing.

I also use the Maxi doser as an ATO and also have a KHD.

I replaced all tubing, for all use cases, with PVC.

What I've found is that any tubing where salt water is, the tube goes very cloudy, this includes my ATO, as I add a very weak solution of salt water to counteract the KHD over the course of the week.

The water coming from the ATO tube is about 2" above the water line in the sump and runs down the side of the glass.
Where the water is running down the glass is also a cloudy, sticky, substance on the glass. This doesn't seem right.

Is the PVC tube breaking down because of the salt water, at this stage I'm pretty much sure it has to be.

Should I use silicone tube where it involves salt water?

I guess this isn't the intended use case for it seeing as this is happening.

Member No 1 · Jul 14, 2020

The PVC isn't breaking down. If that was the case, think of all the tanks both residential and commercial that would be in big dodo.
I would be more inclined to think with the water running down the side of your sump vs dripping straight in, that some sort of bacterial/fungal issue is growing.
Try having the line drip straight in.

ReefPig · Jul 14, 2020

Member No 1 said:
The PVC isn't breaking down. If that was the case, think of all the tanks both residential and commercial that would be in big dodo.
I would be more inclined to think with the water running down the side of your sump vs dripping straight in, that some sort of bacterial/fungal issue is growing.
Try having the line drip straight in.

Forgive me, this isn’t the hard PVC pipe everyone uses, this is the GHL Flexible PVC dosing tube.

It’s their alternative to silicone tube and I believe was specifically created for use with the KHD reagent, as it’s acid resistant.

The reason I was suggested to use this over silicone tube is that it is not air permeable, unlike silicone, and this should prevent air bubbles in my dosing lines.
To this end, yes it has completely prevented air bubbles in dosing, but I also replaced other tubes (ATO etc), which carry salt water, on these lines I am having the cloudy issue.

ReefPig · Jul 14, 2020

This product is what I’m referring to:

https://store.aquariumcomputer.com/en/product_info.php?info=p360_flex-pvc-tube-6-4--5-m.html

Member No 1 · Jul 14, 2020

PVC is PVC, whether rigid or flexible. It might get cloudy, but I'm sure it's not breaking down.
I am using the same product on my KHD for the reagent, so I'm familiar with what you are talking about. I'm sure GHL didn't have it specially made for the KHD, as you can buy it from multiple sources.

flexible pvc tubing - Google Search

ReefPig · Jul 14, 2020

Member No 1 said:
PVC is PVC, whether rigid or flexible. It might get cloudy, but I'm sure it's not breaking down.
I am using the same product on my KHD for the reagent, so I'm familiar with what you are talking about. I'm sure GHL didn't have it specially made for the KHD, as you can buy it from multiple sources.

flexible pvc tubing - Google Search

Thanks for your comments, what I’m looking for is a statement from GHL saying that it’s ok to use to transport salt water through it and that it going cloudy is fine, silicone tube doesn’t do this and it doesn’t leave a greasy residue on my glass from where the water coming from it hits the sump.

I appreciate you trying to help, but I was running silicone for a year without this, now with the PVC tube, in just two weeks, this has started.