Ronald Lao

Wow... this is a cool info literally. It's the first time I've seen this. I do have my doubts on it's effectivity from where I live. I seldom see a clear night sky. I'll probalby see one right after a big storm but most days it's cloudy and such in the evening. But still, it was great info to know.

Aha! Finally understand the multiquote thingamajig! Okay Swansont, I'll shelve the Peltier option for now, since you might be right that it could be more costly startup for me due to the lossy operation. Thanks for this link acme. I'll need to check this out some more. Even a small unit costing 1,200 USD might be just a tad expensive for me to consider, but I'm not giving up hope that I might be able to rig something up myself. I'll have to rummage through the DIY world of absorption refs in the next couple of weeks though. Great input! Yes StringJunky, root chilling is a major concern if you want to be in commercial. I can make the difference between profit and "Let's pack it up". I read up on the link and I'll try to look for the book as well. This lead of yours is simply one of the best input I have gotten so far that is science backed. Majorify of the information I find in the internet seems to be hearsay and trends. Thanks again man! I'll try to give an update as I move forward to in this project so you guys will know how things worked out.

Sorry for my naivete. I thought both are the same. I actually am referring to chalated iron as my need.

According to literature I have read, Lettuce will be bigger at 24 degrees celsius at the root temperature. Probably the same reason why lettuce is usually a "cool weather" plant. Uh... please forgive my newbie ways. I have not been actively in forums for over 13 years and I have to relearn the etiquettes and direct quotes. Thank you for the overwhelming responses and ideas, let me try to give a few feedback. 1. No large body of water near me. I live in the city and space is a big issue. This project is really targetting an urban setting. 2. I have thought about burying pipes underground... from literature and actual small testing, my ground temperature is around 25 degrees celsius. I have actually used this to some advantage as well when I designed the system to have my sump buried 75% on the ground. Burying pipes underground to cool the nutrients would probably be my last option since space is a major issue and the pipes needed are not cheap either. 3. I'm no expert on evaporative cooling, however, my gut feel is that it's probably not going to be very effective because the temp difference is really very small. Example, yesterday the water temp was at 27.9 degrees. 4. 24 degrees celsius requirement is actually for the plant roots because according to research, you can grow lettuce really big if you keep the root temperature at such temps. For a commercial venture this is very important. 5. I know that peltier is a "lossy" device. But one major disadvantage that I have here in the philippines is the cost of electricity. I believe we have one of the world's most expensive electricity. So since Peltier can be operated at low power (i.e. solar panels) I thought it might just do the trick. Power on during the day only. 6. There was another idea I was toying with but I'm not sure if it's uh... legal here. Somebody told me that in some remote areas where their is no electricity they actually use a refrigerator that is powered by a "candle" called an ammonia cooler. It was cold enough to make ice so I guess that could be another solution for me. Barring the legal issue of operating an ammonia based cooler maybe there are other "refrigerants" with the same idea I could use. A solar panel with heating element would replace the candle obviously. Hope these feedback will keep until Monday. I'll be off volunteering as a councillor in youth camp for the weekend. TTFN and thanks again! Electricity rates in Manila, Philippines where Meralco is the provider.

Background: A few months ago I decided to start a small aquaponics (growing fish plus vegetables together) farm in the Philippines. I was hoping to make my production as efficient as possible. One way is to make the plant root temperature lower than 24 degrees celsius. I'd like to find the most cost effective solution to do this. Situation: A recirculating system with about 25,000 Liters of water needs to be cooled to around 24 degrees Celsius. A part of the water system is outdoors but still insulated by 2 inch styrofoam from direct sunlight. Typical ambient temperature during the day can reach up to 32 degrees celsius during summer. Water Temperature is measured to be usually around 2 to 3 degrees cooler than the ambient temperature. Question: What is a the more cost effective solution to cool the water system? My idea is to use TEC/Peltier devices if possible to use very small wattage that can be turned on during daytime using solar cells as power since it's cooler at night anyway. Please include the computations to support as well as your assumptions.

Is there an easy way to make Iron Chelate or at least a replacement for it? I want to use this as an iron supplement for the plants in my Aquaponics garden. Recommended dosing for Iron Chelate is 2 ppm every 3 weeks. Problem is I can't find any Iron Chelate for sale where I live. The Aquaponics environment is as follows: Temperature - 25 to 30 degrees Celsius PH - 6.5 to 7.4 I read somewhere that ferrous sulfate might serve as a replacement. Any help would be great.