Useful Links

Aquaria Links: http://www.aqualink.com

This web site has almost everything that you would want to know about aquariums at http://www.aqualink.com/fresh/chemistry.html. Good articles on water quality issues. 

Aquaponics: http://www.aquaponics.com

Reef Aquarium Web Services: http://www.reefs.org

Great site with a chat channel, discussion board and some great articles.

Koi Web Services:  http://www.koiusa.com

All you want to know about koi and more.

http://www.koivet.com

http://www.vcnet.com/koi_net

Others: 

You can also try the following:

http://www.mops.ca

http://www.aquarium-design.com/chemistry.html

http://www.bestfish.com/tips/102998.html

http://saltaquarium.miningco.com/pets/saltaquarium/library/weekly/aa081298.htm

http://www.amdareef.com/ho_chem1.htm

http://www.geocities.com/Heartland/Plains/3515/maintain.htm#pH

http://kingsoftheaquarium.com

Hydroponics Links

Homegrown Hydroponics: http://www.hydroponics.com

Hydroponics Society of America: http://hsa.hydroponics.org

Esoteric Hydroponics: http://www.blunt.co.uk/manual/index.html  

Practical Hydroponics and Greenhouses: http://www.hydroponics.com.au/current_issue.html 

Hydroponics Gardening: http://www.gtghydroponics.com/phchart.htm  

http://www.soil.hostweb.org.uk

http://www.jackeden.com/tips/phind.html

http://hgic.clemson.edu/factsheets/HGIC1650.htm

Food Links

Food Online: http://www.foodonline.com

http://www.ag.ohio-state.edu/~ohioline/sc172/sc172_13.html

Swimming Pools Links

Water Chemistry for Swimming Pools:

http://www.deh.enr.state.nc.us/ehs/chem.htm

Water and Waste Water Links

Water Quality Association: http://www.wqa.org

American Water Works Association: http://www.awwa.org

Monitoring Water Quality (by U.S. EPA): http://www.epa.gov/owow/monitoring

Water Online: http://www.wateronline.com/content/homepage/default.asp

Water Conditioning and Purification Magazine: http://www.wcponline.com

U.S. Water News: http://www.uswaternews.com/homepage.html