in Aquatic Plants Digest Friday, August 8 1997 Volume 02 : Number 882, Karen Randall wrote "Hot glue is just a plastic that melts with heat and then solidifies again when it cools. It won't hurt your fish." I have noticed that two fallacies are widespread in the aquarium hobby - 1. all plastics are much the same 2. plastics are innocuous for fish and plants. I hope you don't mind if I make this a long post by quoting some sobering info from an excellent reference book, Stoskopf's Fish Medicine [Saunders]. Excerpts follow from the Hospitalisation chapter, Plastics section. --------------------- "Plastics cover a wide range of materials with quite diverse properties." . . . . . "New or unknown materials should be tested for toxicity with a bioassay before they are used with a client's fish. Materials graded as acceptable for foodstuffs are usually acceptable for aquarium systems. Recycled plastics should be avoided." . . . . . . "Newly constructed tanks using fibreglass should be treated carefully to rid the system of polymerising agent and trapped metals in the fibre glass resin." [** He gives a simple procedure for doing this, if anyone wants me to post it]. . . . . . . "[Vinyl] can have tremendous residuals of toxic plasticiser and heavy metals trapped in the polymerisation process. These leach out into the water. Dioctyl phthalate is a common contaminant, and although 10 days of soaking and etching is recommended for its removal, it makes vinyl a poor choice in any fish system." [** But it's widely used ....] . . . . . "Polyvinyl chloride is generally not used in tank construction, but it is used in the construction of the plumbing systems .... High impact or unplasticised PVC is most commonly used for plumbing but can contain trace amounts of metals, particularly lead, which can be leached in acid water systems." [** and of course plasticised PVC is much worse]. <end of excerpts> --------------------- I think toxicity of this kind is common and unrecognised, because MP <pearlsco at u_washington.edu> Subject: PMDD ingredients I am willing to sell PMDD ingredients to people in the United States. I'll need to look into postage rates, but you can email me if interested, and we can figure out how much you want (or how much you'd like to make up in a batch). I am also willing to trade PMDD ingredients for plants. Still looking for an 18" Val, glossostigma, E. tenellus, Hydrocotyle vulgaris, and anything interesting. Of course, all replies should be direct to me and kept OFF the list. Cheers, Mark - ------ pearlsco at u_washington.edu How much does a fish need a bicycle like a man needs... ? ----------------------------- Date: Fri, 8 Aug 1997 02:38:18 -0400 (EDT) From: ac554 at freenet_carleton.ca (David Whittaker) Subject: Re: Optimum current in planted tank Frank I. Reiter asked... >Recently, I setup a pair of 120 gallon heavily planted tanks with a Fluval >403 filter on each one. Continuing with the original plan, today I also >added a Seastorm 240 fluidized bed filter to the output of the Fluvals. > >I was quite surprised to see the throughput of the filters drop quite >drastically, I estimate by a factor of three or four, and I spent some time >pondering whether the added biological filtration as worth the reduced >water flow, and then realized that I really do not know how much current is >good for my plants. > >With just the Fluvals, the current was fairly strong in places, perhaps 8 >inches per second across the front of the tank. Vals at the opposite end >of the tank from the spray bars were tilted 30 degrees from vertical. > >Now, the current is at most two inches per second. Those same vals are >standing more or less straight up with only a slight current visible (via >small floating particles.) > >What would you do, keep the fluidized bed filters for added bio filtration, >or remove them in favour of more current? The val in front of my PRO-4 powerhead are tilted 30 degrees from horizontal. The current is beneficial to plant growth and the white clouds need the exercise. Vigorous circulation of oxygenated water to the far corners of the aquarium will prevent cyanobacteria from gaining a toehold. As well I like the look of water movement. Why not remove the fluidized bed filters? The biological filters are only competing with the plants for ammonia anyway. I'll add that the PRO-4 makes an excellent CO2 injection system. The CO2 bubbles enter the intake and exit in the stream as a fog which disappears about twelve inches from the nozzle. The impeller does such a good job that no bubbles are visible. This pump is the only filtration/circulation in the 180 gallon tank. - -- Dave Whittaker ac554 at FreeNet_Carleton.ca ------------------------------ Date: Fri, 08 Aug 1997 00:05:06 -0700 From: Jeremy <adamsjer at ucs_orst.edu> Subject: Books? I am interested in finding out what peoples opinions are on plant books. I am looking for a very complete and detailed book on aquarium plants that include good color pictures for identification. It would also be nice if it covered place of origin and its basic requirements. If anybodys has a favorite pond plant book, I would be interested in hearing opinions on that also. Thanks Jeremy ------------------------------ End of Aquatic Plants Digest V2 #882 ************************************ To unsubscribe to aquatic-plants, send the command: unsubscribe aquatic-plants in the body of a message to "Majordomo at ActWin_com". 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