I'm sure many of you are tired of me posting about tin leaching from plastic, but for those having "tin problems" this might be helpful.
Although I found tin leaching from many plastic products, I found that plastic tubing may be the worst culprit. I performed "soak tests" where I would soak lengths of tubing (and other plastics) in RO/DI for 5 days then send out water samples for ICP analysis. (Unfortunately, the lengths of tubing and gallons used for soaking varied a little making it difficult to make perfect, direct comparisons, but the end results still remain very significant). Below are 4 plastic tubes that I soaked and the resulting ICP tin results. I also calculated the amount of tin that this would add to a hypothetical 100 gal aquarium (by crude extrapolations from the volumes of RO/Di used to soak the tubes, but not taking into consideration the fact that the lengths of tubing varied. (All tubing had the same pump used to circulate water thru them over the 5 day period; ATI ICP tests were used):
1) Green Tubing (5/8" ID; pump return hose from my tank): 30" soaked in 1.5 gallons....... Tin = 1438; Extrapolated to 100 gal: 22
2) Braided Tubing from Lowes (5/8" ID): 5' soaked in 2 gallons..............................................Tin = 2014. Extrapolated to 100 gal: 40
3) Non-Braided Tubing from Lowes (3/4" ID): 8' soaked in 2 gallons.....................................Tin = 5263. Extrapolated to 100 gal: 105
4) TYGON #3630 (see below); 5/8" ID; 8' soaked in 2 gallons ....................................................Tin = 11. Extrapolated to 100 gal: 0.22
A while back I searched for a more inert plastic tubing and came across a company called Saint Gobain (in PA) who make 30 or more "models" of tubing under the brand name of TYGON. Initially, I could not get their tech support to return my calls or emails and ended up buying one of their "models" blindly on Ebay. But this model (#3603) was too flimsy and after just 4 weeks produced an odd, foul-smelling slime (that I later learned was from a "plasticizer" used in production. (It did, however, leach very little tin as can be seen above).
A few days ago, I finally was able to connect with the company and learned a lot. It appears that TYGON Model #2475 is best suited for our aquarium needs (although there are other models that would also suffice). I was told that there is definitely no tin used in the inner and outer lining of the tubing (but they weren't sure if there is tin in between "but don't believe so". As long as there is none that comes in contact with water then I assume it should be fine).
Unfortunately, this stuff isn't cheap! 10' is the minimum length you can buy @ $8.83/ft (3/4" ID) (plus tax & shipping). But because of all my tin problems and dying SPS, I bought some which will be delivered tomorrow. Eventually, I may do a soak test on this tubing, but probably only if my "tin problem" persists. I bought it here: 3/4" ID x 1" OD x 1/8" Wall Tygon® 2475 High-Purity Tubing | U.S. Plastic Corp.
You can read more about this tubing here:
2475.pdf (usplastic.com)
Hope this might help anyone "suffering" from tin issues!
Although I found tin leaching from many plastic products, I found that plastic tubing may be the worst culprit. I performed "soak tests" where I would soak lengths of tubing (and other plastics) in RO/DI for 5 days then send out water samples for ICP analysis. (Unfortunately, the lengths of tubing and gallons used for soaking varied a little making it difficult to make perfect, direct comparisons, but the end results still remain very significant). Below are 4 plastic tubes that I soaked and the resulting ICP tin results. I also calculated the amount of tin that this would add to a hypothetical 100 gal aquarium (by crude extrapolations from the volumes of RO/Di used to soak the tubes, but not taking into consideration the fact that the lengths of tubing varied. (All tubing had the same pump used to circulate water thru them over the 5 day period; ATI ICP tests were used):
1) Green Tubing (5/8" ID; pump return hose from my tank): 30" soaked in 1.5 gallons....... Tin = 1438; Extrapolated to 100 gal: 22
2) Braided Tubing from Lowes (5/8" ID): 5' soaked in 2 gallons..............................................Tin = 2014. Extrapolated to 100 gal: 40
3) Non-Braided Tubing from Lowes (3/4" ID): 8' soaked in 2 gallons.....................................Tin = 5263. Extrapolated to 100 gal: 105
4) TYGON #3630 (see below); 5/8" ID; 8' soaked in 2 gallons ....................................................Tin = 11. Extrapolated to 100 gal: 0.22
A while back I searched for a more inert plastic tubing and came across a company called Saint Gobain (in PA) who make 30 or more "models" of tubing under the brand name of TYGON. Initially, I could not get their tech support to return my calls or emails and ended up buying one of their "models" blindly on Ebay. But this model (#3603) was too flimsy and after just 4 weeks produced an odd, foul-smelling slime (that I later learned was from a "plasticizer" used in production. (It did, however, leach very little tin as can be seen above).
A few days ago, I finally was able to connect with the company and learned a lot. It appears that TYGON Model #2475 is best suited for our aquarium needs (although there are other models that would also suffice). I was told that there is definitely no tin used in the inner and outer lining of the tubing (but they weren't sure if there is tin in between "but don't believe so". As long as there is none that comes in contact with water then I assume it should be fine).
Unfortunately, this stuff isn't cheap! 10' is the minimum length you can buy @ $8.83/ft (3/4" ID) (plus tax & shipping). But because of all my tin problems and dying SPS, I bought some which will be delivered tomorrow. Eventually, I may do a soak test on this tubing, but probably only if my "tin problem" persists. I bought it here: 3/4" ID x 1" OD x 1/8" Wall Tygon® 2475 High-Purity Tubing | U.S. Plastic Corp.
You can read more about this tubing here:
2475.pdf (usplastic.com)
Hope this might help anyone "suffering" from tin issues!
