Backyard Aquaponics
A place to discuss aquaponics

Have people had much problem with evaporation from their grow beds?
how often are people having to top up their systems?

How long is a piece of string ! all systems are different volume of water how often you flood how high you flood temperature in your area
I have not added water to my system for 2 months
I am shore othere will telll you the same

Sometimes I add a little. Lots of room to move on my system so its not important to monitor.

Over summer months, with no rain, I was adding about 400L a week in a 3000L main tank with an 800L sump. I was without a great deal of plant matter so evaporation would have been higher. I reckon that the plant cover would reduce evaporation, maybe increase transpiration, but evaporation is the biggest water loss.

In the scenario of empty growbeds perhaps... but I'd disagree with a fully planted growbed in summer... transpiration is the major loss...

And 10% - 15% loss seems to be the reported consensus

I'm adding about 10 gallons a week to the barrel ponics system, no leaks ground dry as a bone. 47% humidity. Its usually at least 75 to 80 around here in the summer. Grass is dying but I hadn't got weak enough to water it.

+I Rupe
Transpiration can be a big water mover. Across the range, it seems that plants transpire 90-450L of water to generate 0.5kg of solid plant matter. A single tomato plant transpires about 136L over the growing season. I guess certain veg (toms, cukes etc) will also lock up a good amount in the fruit too.

I love when we get to the science of it, 136 gallons for 1 tomato plant explains a lot! Veggies are crazy this year!

... it might yeild 20kg of tommies

Bill, i`m an avid collector of unusual/strange facts and figures
Its litres not gallons hehe

I'll do better next time, sorry!

I guess litres may relate to soil grown, EB`s tom plant from a couple of years back would definitely be gallons
viewtopic.php?f=3&t=644&st=0&sk=t&sd=a&hilit=tomato+weight&start=30

Yep, transpiration uses a lot of water during certain weather conditions. Plants like their humidity a certain way and they have the power to increase the humidity around them by transpiring water if they have access to the water to do it with. Ya don't want to stop transpiration since that usually means killing all the plants and then you have to do water changes to keep the nitrates in check which kinda defeats the purpose.

There are losses due to evaporation too, the more surface area exposed to air and the more splashing and bubbling there is, the more evaporation will happen too. But those things also make for better aeration in a system which is really important too so I wouldn't try too hard to eliminate evaporation.

Anyway, the amount that systems need to be topped up will vary greatly depending on size, season/climate/temperature/humidity, types and amount of plants in the system, and amount of surface area/aeration in the system. In any case, the water usage is still far less than most dirt gardens or even hydroponics since Hydro usually requires complete system dump and nutrient replacement at least every few months.

I've personally got my system hooked up to automatic top up valves (float valves) that will add water if the system gets too low so I can't tell you how many gallons of water I'm adding in a given time period. I can say that the only times I usually hear the valves open up is when I've taken system water to use in the dirt garden.

have you thought of using one of these?
http://www.besflowmeters.com.au/
my future system will be plumbed to top its self up and i think one of these meters might find its way in there.