Solar pump
I came across this at jaycar today.
1.6m head.
A light sensor could be used to enable swithing to a 12v battery for night operation which could charge during the day off of a 12v 4.5W solar panel also avaliable at jaycar.
http://www.jaycar.com.au/productView...2&form=KEYWORD
I looked at that as well but then I did some calculations. If I have a grow bed that is 2.4mt long X 300mm high and 600mm wide then I would have .4 of a cubic metre. This equates to 400lt and at 200lt/hr that pump would take 2hr to fill a flood and drain grow bed
Kev,
That's not quite right though, as you're not accounting for media in the grow bed.
I'm sure someone can give some actual figures, but i would think media could account for anywhere between 50% and 80% of volume and therefore change the figures.
I agree either way it's much slower than a 2000L/h pump or something, but thinking green etc maybe it could work?
Bobby - my concern would be ensuring adequate aeration of the fish tank with a slow cycle. But i think it's worth investigating further (you could always use a few of them after all...)
Rob
This issue comes down to the energy used to carry out a given task. Setting aside variations in efficiencies, for example, to elevate 1,000 ltrs of water 1.5 mtrs in height will consume X units of energy. Moving it faster will mean consuming X units quicker and conversely moving it more slowly will mean consuming X over a longer period of time.
Essentially the more water and the higher you want to pump it, the more energy is used.
As far as the Jaycar pump goes, 200ltrs/hour is likely to be the optimal pumping rate - with no elevation. It's anyone's guess how much the flow would reduce due to elevation as the spec's don't say. At 4.5W/12V that's about 0.2A.
Looking around on Ebay at say a 0.85A 12V pump (search "Solar Powered Water Pump 12V 850mA") This one pumps to 3.5mtrs and a max of 650 Ltrs with no elevation. Lets guess that at 1.5 Mtrs it'll do 250ltrs/hour. Actually I have one of these coming (not for BG use) so could test for you in due course.
A typical IBC GB (1.2 x 1 x 0.3 deep) with media = .36 cubic metres or 360ltrs. As per Rob above, assuming 2/3 media and 1/3 water that's 120 Ltrs of water in a GB. So the GB would cycle around twice an hour. More importantly how many times is the FT being cycled? Reading on the forums my understanding is a minimum of at least once per hour.
The other issue that Murray has pointed out in the past is the lifespan of 12v pumps. Compared to 240v they are limited and many don't have a 'continuous' duty cycle....which may mean premature failure with it's associated fall out - dead fish?
Marky Mark
"Some people tiptoe through life, so carefully, to arrive, safely at death." ~ Jermaine Evans
The other thing about solar powered pumps is what are you going to do for night time?
If you go down the charging batteries road, I'd recommend investing in some way of running the pump less often at night, as that is much more expensive than during the day for solar powered systems. This is why solar/wind hybrid systems do well, as there can be wind power provided during the night. The easiest and cheapest way I can imagine to run the pump less often at night is with a timer based flood/drain system. You might also consider only running the aeration system at night and leave the filtration for day time operation only. You would need low stocking densities for the size of the fish tank to accommodate the ammonia build up overnight.
Also take note that charging a battery takes about 50% more energy that what you can get back out of it. So take a 2 amp hour battery being charged at 1 amp, it will take about 3 hours to charge, but could only provide 1amp for about 2 hours, the rest of the power put in is lost to heat during the charging.
Due to this and some other factors, I worked out one time that I would want a solar array power rating of about 7 times more powerful than the load it runs. Also a battery bank large enough to run the system during cloudy days. Cloudy days are another reason solar/wind hybrid systems do well, as it is usually windy when it is cloudy.
Last edited by davidl; 16th March 2012 at 19:40.
My DIY main and 1st AP system - Learn from the mistakes I made with this system
My small, cheap, simple, basic DIY AP system
Info for beginners: Number of fish you can keep does NOT just depend on fish tank size. It mainly depends on the amount of aeration and amount of filtration, ie grow bed size. If your fish will be large enough to eat or messy like goldfish, then start with no more than 1 fish per 20L (5.3 gallons) of GROW BED volume, is my advice.
I've tested the following "Solar Powered Water Pump 12V 850mA" (10.5W) and can offer the (approximate) results:
390 LPH @ 0.1 mtr head
330 LPH @ 1.0 mtr head
245 LPH @ 1.9 mtr head
(rounded to the nearest 5 Ltrs)
This was carried out using a 1A 12v power pack and 3 metres of plain old 12mm garden hose.
I guessing the dramatic difference between it's rated 650 @ zero elevation is attributed to the length and diameter of the hose I used rather than the 0.1 mtr head. I also didn't test the voltage under load.
Marky Mark
"Some people tiptoe through life, so carefully, to arrive, safely at death." ~ Jermaine Evans
A long skinny hose will make a big reduction in flow rate.
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