Backyard Aquaponics
A place to discuss aquaponics

I don't know a good way to clean up the bottoms of sumps, DWC, Duckweed beds, wish I did. Anything you do is going to disturb the stuff and send it floating through the system and most of it is probably so fine that a lot will escape whatever you use to scoop it up. It is the biggest complaint I have about DWC right now, is that there is no GOOD way that I can think of to do this cleaning. For a large system it is a MAJOR event.

I'm sensing a brain storming session coming on lol. I'm thinking a sump pump and a modified pick up similar to a pool vacuum??

How do these roots look for dirtiness?? The seedlings couple weeks old so roots maybe 1 week.

Its a sad day today, i went down to the bees to do a harvest and they have abandoned hive. Bloody hive beetle got a hold when the beetle trap overfilled. Now i have to start again, go find a swarm or call on a mate to get a few frames to start a new hive. The up side is i get to start them in the green house, I'm over manual pollination.

Roots look good. Seeing some extra algae but the roots look white which is good.

Thanks mate, they were a little greener today when i transplanted them so keen to see how the permanent planks go.

Ok so here is a pic of my lettuces at 20 days from sowing, they have really slowed down now and think it is maybe the algae being the cause. Sorry forgot to take a pic of the roots but they starting to go green however no late deposits on them. Things like the corn that have large roots i can just wipe the green off but the lettuce has fine roots and although i can wipe some of the green off it generally breaks a lot of the roots off.
Any ideas??
I am fitting a filter to the system in the next week or so but don't think it will help much with the algae issue.

Isn't it completely dark under those rafts? how come algae can even grow, I thought it needed some light at least?

Agreed, not sure other than it may be growing mainly elsewhere (DW Pond) and spores are moving through the system. Its not getting a hold in the DWC i guess because it is dark but it is present and enough to slow things down?? I do have a gap at 1 end of the DWC where the water enters, i think i will need to make something up to block it out also.
The main issue in the DWC is the algae film on the bottom that once think enough floats up in lumps.

Well if it is not growing in the DWC then perhaps some kind of screening of the water before entering the DWC like you mentioned... but that does add one more thing to maintain.

If there is floating algae flowing around in the water throughout the system, it will not only be using up oxygen at night but also nutrients for the plants. Algae decomposing in media beds can actually have an inhibiting effect on future algae growth through the system but you need to get the algae to die off and be deposited into a place where it can decompose without causing an oxygen depletion situation somewhere. Flood and drain beds are ideal for this since they can't be depleted of oxygen unless you so totally clog them up that they don't drain.

Of course if the weather is too hot there, lettuce may suffer or if there isn't ample aeration under the rafts one might also see a slow down in growth.
What are your nitrate readings?

BOGI Planting Guide (Google cache as site is down).

There is a book available from BOGI that is worth the purchase, the QLD Planting Guide. Site is down or I'd link it.

Hi TCLynx, I am hoping the problem is caused by the DW Pond and now that is is just about completely covered in DW i hope my problem will go away. Its also been quite warm so i imaging as the weather cools off it should also assist.
Not sure about the Lettuces, it is still warm but i see Hydro guys growing them fine around here out in full sun so imagine i should be able to grow them. The roots do have a residue deposited on them so may be the issue or at least contributing to it.
I have very slight readings of nitrites and about 5.0 ppt or less of nitrates so nutrient shouldn't be a problem. All other reading are good.
Oxygen has been in the DWC for over a week now so that shouldn't be an issue.

Thanks S.O.P, yes i considered that planting guide when i put my schedule together.

So my lettuces are growing slowly but whats your thoughts on the colour and patterns in the leaves. Can see 1 is pretty much yellow and the one next to it has an un-healthy looking pattern.