fiberglass screen

[sideways]

I'm using fiberglass screen on the top of my tank to help it breathe a little better and keep it cooler. I want to close off my skimmer outlet too. Is the fiberglass screen ok to use under water or should I use something else. I was thinking of buying one of those green fish nets and cutting the netting out and using that, but I already have the screening so if that'll work it would be cheaper. Do you think I should seal it on with sealent or just rubberband it on?

 

[Energy]

An actual fiberglass screen doesn't sound like a very good way to go. Have you ever rubbed fiberglass on your skin? That stuff really hurts! The easiest way to go is to a fabric store and buy very fine but strong window curtain material. It is breatable but tear resistant. Cut to fit over the top of your tank. Secure with silicone sealant. The light and air can pass through. Another option might be to use window or door screen mesh you can buy from Menards or Home Depot in rolls. Just make sure it is not metal but the plastic kind of course.

 

[sideways]

Its not really like fiberglass because it's coated in plastic. It looks just like window screen material, except very soft like cloth. I bought it at home depot, it's mostly used as mosquito netting. If you go to a site like reefcentral.com, it's the prefered material for screen tank tops. I just don't know about putting it in water with octos, since they're so picky.

 

[sideways]

nevermind, I cut the netting out of a fishnet

 

[mikeconstable]

Unseen hazards?

Don't know what would keep a determined ceph in its tank - watched a octopus trying to lever its way round a siliconed-in corner system.
I once used an old nylon toothbrush to try to clean something in a tank.
Cuttlefish grabbed it so I let it go rather than fight, but it chewed bits off it and died later - ingested food goes too close to the brain in cephs?
I worked in synthetic resins (plastics/polymers/fiberglass) for years, so know a little about additives - they make things possible / economic but complicate their suitability for marine systems.
Anyone know if phthalate plasticisers are still used in aquarium PVC tubing? - they were being tested in uk "cling film" 30 years ago, later eliminated.
(Phthalates are phytotoxic, kill plants in hot PVC polytunnels, but continued to be used as cheap plasticisers for years, until at least 1990's).
PVC used to have lots of nasty stabilisers and other additives, apart from the problem of waste disposal -
Ban PVC (!?)
( and other halogenated horrors?)

 

[Steve O'Shea]

Interesting stuff Mike!!! Any idea why squid die in polyethylene tanks (I've not been able to prove it, but it's this gut feeling, having suffered heavy mortality in them before, and considerably less mortality in the likes of fibreglass and concrete).

Any light you can shed on this would be greatly appreciated.
Cheers
Steve

 

[Nancy]

Hi all,

While we're on this subject - I was told recently by the water expert at a large grocery store (they sell all types of water and make their own RO/DI water there) that I needed to use rather expensive polycarbonate containers for RO/DI water. He said that cheaper plastics would leach substances into RO/DI water. This is not the first time I've heard something like this - is there any scientific basis for this theory? What should water containers be made of?

Thanks,
Nancy

 

[WhiteKiboko]

well, i dunno about what could get into the water, but i can offer a possible alternative.... i know for a fact that you can get 5-6.5gal glass carboys at homebrew stores and probably some hardware-type stores.... although compared to plastics theyre quite heavy (nevermind they hold 40+lbs of h2o) i dont think they present a probelm, although im the first to admit im not an expert....

 

[mikeconstable]

Polyethylene containers

Steve, thanks for your thought on polyethylene - maybe feelings can be checked out or trouble avoided. I too have heard that polycarbonate is the best material for water (mineral water is sold in that or glass), and can still remember polyethylene water containers used to impart a characteristic odour to the contents! Home brew kits in UK still use 5 gallon polyethylene containers, and I have carried a lot of water in those.
Re polyethylene:--
This would be my favorite material for an environmentally friendly container - a simple, relatively inert starting substance producing a product with useful properties. Most other starting materials for polymers are inherently more toxic - Vinyl Chloride, Styrene, Butadiene, Acrylic and Methacrylic esters, Amides, and the base for polycarbonate (which I cannot remember, but is another to be avoided if possible!), etc.
I do not know what materials are used in production apart from ethylene (a gas), except iron is probably used as a catalyst in the polymerisation. The product would be substances with increasing molecular size and inertness as polymerisation proceeded but I suppose that these could contain a 'reactive' double bond, and ethylene itself does have the (physiological) effect of ripening fruit (and flowers).
My other thought is that squid might not avoid physical contact so easily with something 'softer' or less dense than rock?
Sorry if this is getting technical - I don't know if it is helpful in a forum like this but it is at least making me think, and where else do the finer details of our effects on life come from?

 

[mikeconstable]

Polycarbonate containers

Bisphenol A is the component which I could not remember - it has just hit the headlines again for chromosome damage to mice (BBC NEWS | Science/Nature | Chemical linked to mouse genetic damage, BBC, science site). Other internet sites say heated, scratched, old or cloudy polycarbonate bottles leach Bisphenol A at higher rates.
Lots of dangers to life on earth, the big bad ones are known and tolerated (cars, Monsanto?), now we shall have to avoid the subtle ones sneaking up the fast lane.

 

[mikeconstable]

Polyethylene containers cause squid mortality?

Traces of hydrocarbon chemicals could cause problems?
An article in "The New Scientist" (5 April 2003, p.16) claims that extracts from molluscs (mussels collected from beaches known to have been oiled) are toxic to healthy mussels, after removing all identifiable compounds.
I would like to have read that extracts from 'clean' mussels did not have the same effect to make sure that it was not some artifact of the testing.

I wonder if a release-agent is used when forming polyethylene?
Whether polyethylene film (sheet) lining another container would increase squid mortality, or whether it is only worse in thick-walled polyethylene?
Any thoughts, Steve?

It's a funny world -- poly-vinyl alcohol has been used as a mould release in glass-fibre constructions, and as a major component in making bundles of glass filaments into a fibre! (I have heard that the boat manufacturers don't use that type of fibre as it makes the hulls more water sensitive because poly-vinyl alcohol is soluble in water!)