Backyard Aquaponics
A place to discuss aquaponics

I have a 700 litre pond. It is now about 3 months old and now that the weather is warming up the plants are starting to take off (tomatoes, snow peas, lettuce, baby spinach, parsley).

REcently I have noticed a great increase in the water I lose from the system each day. I seem to be losing about 5-8 liters a day (about 1% of total water volume every day).

A lot of literature warns that water loss will occur as the plants grow, but I'm not sure if losses of liters a day are normal?

Are other people experiencing similar losses? Or do I have a hole in the pond casing?

David C.

8 liters sounds high!... my plants are only just taking off too, so I cant help there
how big are your growbeds?
Are you running bubblers?
is there a lot of splashing?

No bubblers, a bit of splashing.

Not excessive grow beds. My growbeds consist of:
7 young tomato plants, about 15 cm high
6 snow peas, about 45 cm high
1 parsley (a small clump)
6 small baby spinach
8 small lettuce

EB, and Steve a while back had leaks of the hard to find intermentent type, I believe it was a spray from the fill grid piping, hitting a rock or something. Look it all over carefully as it goes through its fill and drain, checking for signs of misting and or drippage. Seems a bit to much to just evaporate.

GF beat me to it - sounds like a possible leak... I last 100L in my IBC over the past 2 days
Turns out my son had managed to crack the seal on the valve at the base of the IBC - once secured (and wired up) all is well again!

I was thinking that the larger the surface area including the grow beds would release a fare amount of evap plus takeup via the plants.
What surface area is the pond Aelderic?
Is it in a wind prone area?
C1

now this is why these forums are so good - different people with so many approaches to the same situation...
Yep, if there is a lot of air movement, some splasting and a lot of plant growth then perhaps... but still a bit high for 5-8 liters a day ... just seems a lot of water per day

I've been loosing quite a bit of water now that the weather has warmed up, but have not kept track of it, as i occasionally grab a buck or two of system water for the dirt garden.

Will re-fill soon and monitor the levels for you.

As a side note, the heaters were taken out of the tank a few weeks ago. temp was holding at about 14C. yesterday was 24C most of the day, and today was a beautiful 30C! checked 1000L tank temp tonight. 19.5C happy days are comming.

Steve

The fish arent drinking it are they?

That sounds fairly normal for evaporation.

Evaporation in summer time can be quite a bit, about 275mm a month for in Perth. That means that 9mm a day is disapearing from your tank everyday.. Winter isn't as bad at around 70mm a month, only about 2mm a day.

So a fish tank that is 2m in diameter will be losing 219L of water a month in winter, and 836L a month in summer ( if my calcs are correct). And thats only evaporation, that doesn't take into account the plants growing and transpiring..

Theres some great info about evap rates here:
http://www.bom.gov.au/climate/averages/ ... tion.shtml

now i'm glad that my tank only has a 1m footprint

I mightn't be able to see the fish well due to the depth, but it will save on evaporation

Thanks EB. By those calculations, and allowing for the various pros and cons that various people have mentioned (it is in a wind-prone area, the surface area of the tank is small, but surface area of the growbeds is big, but it is cooler here than in perth, etc), I am losing about what you would expect. Actually, it could be worse, and probably will be in the next few months.

This surprised me, I am losing 1% of my total water volume per day...... and in mid-summer with larger plants this will get worse! I would like to either slow that rate, or use the water loss more effectively.

My first thought was a film of plastic across the water..... but obviously that has problems. Some thoughts:
- Reduce surface area of tank (has the same problem as the plastic film idea.... this will require better aeration, so that the fish can breathe)
- Most importantly, reduce losses from the growbeds. This is where most of my loss is likely to be occuring. Keep the water below the level of the grow medium, never allow it to be exposed to air, cover the growbeds, only leaving holes for plants, optimise the flood and drain cycle. Lots of possibilities. I will start making side-by-side changes to growbeds and measure water in and water out in the side-by-side growbeds.

Thanks everyone!

Cheers,
David C.

I have been thinking of growbed covers that only allow the stem and adequate growth space to be open to the air.
My thinking being, reduced light to effect bio zone and reduced evap.

wow, it was a lot higher than I had expected... guess I never notice in my aquariums as they were always 98% covered with glass...

That is one misconception cleared up for me I guess
Glad I followed this thread!