Backyard Aquaponics
A place to discuss aquaponics

Thanks for your excellent question, jrl91rs.

The bamboo are planted in a ring concentric with the tank and 7m from its wall. One tall species, Oldhams Bamboo (Bambusa oldhamii), predominates but every third bamboo is a different species/variety. Oldhams Bamboo, also known as Giant Timber Bamboo, is certainly not a giant but can reach 20m in height when grown in favourable conditions. The conditions I offer it aren't particularly favourable but I have it growing to about 11m elsewhere on my property so it should be able to achieve this height in my tank planting, especially since it will be receiving FT water to supplement its twice daily irrigation.

The sky is big at my place with very little to interrupt the skyline. Consequently, the hot afternoon sun in summer beats on the concrete wall of my trout tank for half a day until it finally slips below the horizon when only marginally shy of 90º to it. This bamboo screen that I have planted will protect the tank wall from the sun for the last several hours of its transit each day. Additionally, much shade will fall on the almost bare sand surrounding the tank and the general area will be noticeably cooler as a result. These changes have got to make a difference to the tank water temperature.

I could have planted the screen closer but I am keeping my options open for the intermediate area and also I don't want too many leaves blowing into the tank. Everything is a compromise, one way or another.

He PJ, whilst we are on the topic of bamboo, and I know you have good understanding of the material, Ive been thinking about using bamboo quite extensively for my new system as I will have access to a heap of it. My question is how well does bamboo fair in the long term in direct sunlight? This is after being cut and used as a building material.

Scotty, I thought about setting up some micro sprays, or even several strips of towelling, etc going from inside the tank and over the lip to the outside to acts as wicks. I think for this to work reasonably effectively I should have hessian (burlap) for the skirt rather than the non absorbent shade cloth. Perhaps a wafer of (damp) hessian between concrete and shade cloth would do the trick and is certainly something I will investigate for next season.

As I suspected, it is a case of too little too late because I had the grim task of scooping out floaters this afternoon when I came home from the 'big smoke'. I wasn't home last night to scoop out the cruisers (trout cruising at the surface), as I did the previous nights, and my theory has now gained credence - cruisers turn to floaters within 24 hours.

I have no shortage of quality water to pump into or spray onto the tank, so that is not really an issue. If I wasn't so averse to waste I could perform sizeable water changes since my ground water is probably about 6-8 degrees cooler than my FT water. Until I come up with a plan to utilise a 30-40kL water change, because I think that is what it take to drop the FT temp by more than 2ºC, I will concentrate on other means of cooling/prevention of warming. In the meantime I will no doubt suffer casualties.

Interesting question, Charlie, and not one that can be answered simply since so many considerations are involved.

Factors that affect the durability of cut bamboo in the type of situation to which you refer are as follows:

- the species of bamboo
- the age at harvest of the particular culm (cane or pole) from which the piece was sourced
- the season when harvested
- the method of curing used
- the climate where the bamboo will be used
- the prevailing conditions where it is to be used, eg in this case it will be in full sun but other conditions to be considered are its exposure to wind and/or frost, whether or not it regularly gets wet from irrigation, if it is partially in the ground, etc
- the prevalence of destructive pests such as the Bamboo Powder-post Beetle (Dinoderus minutus)) and Bamboo Longhorn Beetle (Chlorophorus annularis)

The short answer is that untreated bamboo culms will deteriorate, if left exposed, and eventually rot or be eaten by pests. You may get 2-3 years or 8-10 years, depending on how much you bother with the info here and elsewhere, and with your prep.

My advice is to try to find out the species that you have available since some are definitely better than others, structurally, and it pays to know what you are dealing with. Whichever species it is, the culms that you harvest should be at least three years old so that the starch levels are lower and more acceptable for construction, and less palatable to the borers mentioned above.

If you are cutting the culms yourself then do it in the dry season and leave the culms standing upright in the clump where you cut them (I will assume it is clumping bamboo but that is another reason why you should determine the species, if possible.) Leaves and branches should be left intact and the culm allowed to stand, on a rock or beer can (not XXXX), for 3-4 weeks. After this time the bamboo culms should be trimmed and then can either be soaked underwater for 2-3 weeks and then air dried, or just be air dried under cover on racks for a few more weeks, or until required.

Bamboo to be used for building purposes, or for any use outside in the weather, can also be heat treated, chemical treated, painted with varnish, and so on. All of these methods work to some degree in extending the life of bamboo. The Sap Replacement by Expiration technique involves standing the freshly cut bamboo culms in a bucket with either copper sulphate or borax for up to a couple of weeks, then air dried as before but for two months.
Another good method is the Boucherie Sap Displacement system. It is designed around the use of a pump and PVC pipes so is right up your alley, Charlie, but I will leave you to research it.


PS If no-one seems to know what the species is then send me some pics - general shot, culm closeup, leaf closeup - and I will have a go at identifying it for you.

Very informative, thankyou.

I will do some investigating.

Hiya PLJ, sorry to hear about your fish. I have several low cost ideas for tank cooling for next year but this year I have a sprinkler head on the inlet to the ft which I turn on in the arvo and this has lowered the tank temp by several degrees and created extra aeration too. Surely even just spraying the concrete walls will provide cooling via evaporation.

Thanks, Skegg. You are right, spraying water onto the tank wall will lower the tank temperature, at least to some degree, through evaporation. I have thought about doing it, even planned to do it, but like so many things at my place it just didn't get done in time. There are several leaks in the tank wall (documented previously) that contribute in some small way along these lines, but are you saying that simply spraying water onto the water surface lowers your tank temp? I could easily do that, in fact I am doing it in a fashion with a 10.6kL pump that I use just to circulate water, but I turned it off during the heat of the day believing it would raise the temperature, just as my recirculating GB water has raised the temperature of the tank considerably. I need to look into that before next year's effort.

The truth is, there are many things that I could have done that would have made a difference which, applied cumulatively, may well have got me through summer with RTs alive. (There may yet be some alive since they aren't all accounted for, just no sign of them.) Not having done some of these fixes/modifications meant that the temperature of my tank water was continuing to rise that little bit faster over a period of weeks than it would have otherwise until, once the really hot spell was on us, there was almost nothing I could do that would make a big enough difference to matter. Put another way, the temperature of the very large thermal mass of my tank's volume was not going to shift downwards appreciably using the techniques that would have best been employed to keep it from rising in the first place.

I have read words along the lines of, 'No pictures? Then it didn't happen!', many times on this forum so thought I would post an image as proof of my successful trout tank Goldfish spawning.

Here are a couple of fish about 7cm long that definitely weren't in the tank when I introduced the Rainbow Trout back in May, although their parents were.

I harvested the remaining leeks from my system, yesterday. I thought they were garlic plants when I put them in and still wasn't sure when I harvested the first one a while back since it had an unleek-like bulbous bottom.

Most of them were slightly rotten at the base and required a bit of cleaning up, ie peeling back an additional layer or two to reveal clean, white flesh. It was quite 'on the nose', too. Is this normal for AP leeks, have I left them in too long, or is there some other explanation for their manky state?

The couple of tomato plants in one of my GBs seem to have gone feral. There are a few small green fruit but clearly there is a disproportionate amount of foliage. There is a squash plant in there somewhere, too.

Thanks for the detailed info about the bamboo PLJ, I am looking at replacing our pool fence some day and I'm interested in making my own Japanese style bamboo fencing (tied together) because I think it would look cool. Didn't know bamboo needed so much care after harvest.

I'm glad the bamboo info was of use to you, Dave. Bamboo fences are very appealing and I wish you well with your pool fence project. I have a book by Iaso Yoshikawa titled 'Building Bamboo Fences', that has a wealth of information in it concerning all aspects of Japanese bamboo fence design and construction. It may well be worth your while to look it up.

I think you have left your leeks in to long, I pulled the last of mine out and they were a good size on the bottom but the white part was not very tall compared to commercial varieties.

Will be interesting to see the growth of the bamboo over the years. How long before you ecpect to benifit from the planting? Have a great 2014.

Thanks for your new year wishes, ccBear: I hope life is good to you this year, as well.
I am already benefitting from the aesthetics of the bamboo planting and should get some decent late afternoon shade on the tank wall by next summer.

Good book recommendation, thanks again!