Backyard Aquaponics
A place to discuss aquaponics

The salinity has been slowly declining due to evaporation, but 32mm of rain over about 20 hours to yesterday morning added over 200l to the system, bringing the salinity down again.




The water has been slightly murky the past few days due to me scooping out some fish poo from the sump, alhough I can still easily see the bottom of the FT.
Ammonia has been around 0.25 and Nitrites around 0.25-0.5 since then, perhaps due to me stirring things up a bit. Nitrates as best I can determine are somewhere in the range of 50-80ppm, tested with straight and 1/5 concentration, but I can't say the colour matches all that well with the undiluted test.
The rain didn't change the pH at all, which is staying very consistent with the shell grit buffering action, even with the increasing feeding rate.

Given the relatively warm weather for this time of year, keeping the water temp mostly in the 10-15C range, I reckon the Ich should have been eliminated after 4 1/2 weeks, so I am planning to remove some salty water from the system to bring the salinity to under 2ppm, as preparation for putting in my strawberry tower.

I often see it written that strawberries wont grow at 3ppm, the question is: will they grow well at 2ppm, or only just survive at that concentration... or should I take salinity down to near 1ppm? I only have rainwater from the roof here, so dont want to have to use more valuable water from the tanks than I really need to.

The only thing evaporation will be doing to your salinity is increasing it. The salt will not evaporate, the water will though

If you dont want to waste water while reducing your salinity to something the strawberries will tollerate, you could use your AP water on your garden. I used to do that occasionally in my potted herbs and they would go mad after a drink of AP water.

oops, what I meant to say was slowly increasing, as the graph shows... ( I should proof read a bit more thoroughly before posting!) but the rain did bring it down. I wont be carrying thousands of litres up to the garden by hand, but will run some of it onto some fruit trees and blackberries, although the ground is already quite wet enough and more water probably wont help... but the question remains, how low do I need to take it to grow strawberries, without the strawberries suffering from the salt?

I did look at the graph and think to myself that it was trending up

You could always put a hose on your pump briefly

Cant help with the max that the salinity could be, but im sure people are having success at 1ppm. Which is a good level to be running it anyway

Plants continue to grow very well, aphids need controlling on the cabbages fairly often, some nice cauliflower heads are developing, and the chard is delicious



Salinity shows its usual slow increase in concentration due to evaporation, and the dip is due to a partial water change when rinsing the gravel in a new bed, which I plan to plant out soon. pH remains very steady in the 7.2s all week, and today: Ammonia 0ppm, Nitrites 0-0.25ppm, Nitrates ~100ppm. Feeding up to 75g some days, with a couple of days about half that when they weren't interested in eating much.

My FT->ST SLO is near its limit, something I knew this was coming, and yesterday found the limit. My current 40mm vertical and 50mm horizontal pipe SLO can handle 5 draining GBs ok, but 6 is too many at the current 10 min GB fill time flow, so I dropped my F&D cycle from 40/20 back to 30/30mins during the day, and I'm mostly running 15/45 with a couple of 20/40s overnight. I turned back the flow to each bed a bit too. The FT filled more than I'd like it to, but didn't overflow, and the sump empties to the top of the pump, but still above the inlet with the old 40/20 cycles.
I'll have a 50mm vertical and 50mm horizontal SLO in place in a day or 2, and that should give me enough extra SLO flow capacity for now, and I'll add the 40mm pipes as a 2nd SLO when required- that will probably after I add the 7th and 8th GBs and strawberry tower - which will be after I drop the salinity a bit more.
Salinity down to 2.53ppt after flushing some of the dirt and dust from the 6th GB and adding some replacment water. Even with the flushing, the FT is pretty murky, I can only see about half way to the bottom, but the fish were still enthusiastic about their breakfast pellets

Hi, like you i have a Davis vantage pro 2(with FARS) I use it to run my weather site. It has the solar and UV sensors along with the normal temp,humidity wind etc I would be interested in a bit more info on the additional sensors you have in order to create the graphs. I use the Weather Display program to plot the data and also have cumulus installed but don't use it much.

Not sure if others would have the same interest so you could PM the info if you prefer.

TIA
Derek

Hi Derek, here is fine, it is on topic for my system thread

I log at 1 minute intervals with Cumulus and import the monthly data file (currently using July13log.txt, found in the data directory of Cumulus) into OpenOffice 3.4.1 (newly released ver 4.0.0 has a bug which limits you to 10000- rows of data, so I've uninstalled it). I also import data from my USB data logger file, which I save weekly, and which is also set to log every minute, so I can display air and water temps on the graph. I then manually enter my pH and salinity readings, which I record about daily.
The USB logger only has 0.5C precision, which is the reason for the lumpy plot, and will log for 11 days at that sampling rate, but you could use less frequent sampling, say 5 mins, and it could store well over a month of data. Having the sampling rate the same as the weather data makes importing and plotting much simpler.
I guess you could use any waterproof temperature sensor in your FT (maybe soil temp?) with the Davis to better integrate it all and save a bit of spreadsheet work, but here I would have needed another transmitter, as the Davis is about 50m from my AP system.
I could send you a link to the file to download if it is of use to you, I have it hidden away on my web page for the Open Office guys who found the problem with the 10000 row limit. It should be ok to open with any MS spreadsheet software too, if you use that.

Yes is use MS software, the link would be great thanks.

Been looking at the price of the davis extra sensors looks like i'll have to wait for that, in the mean time i have also been looking at the arduino options, very intresting and a damn sight cheaper.

The 3 New GBs I've installed in recent days all have some plants in them now, partially from one of the existing GBs which I had packed a lot into, and it now has one of my GB support stands under it in place of the concrete blocks. I used some system water and some new water to flush some of the dust and sediment from the new Canna clay and river gravel, which is mostly of a larger size than in the previously installed GBs, as it was quite a bit less expensive. The drop in Salinity is due to all the new water I added to the system, although you can see a slight rise in salinity from the clay balls on 29-30/7. I put a few strawberry runners in one GB when the Salinity was around 2.5ppt, and they seemed ok, and now it is down to 2.05ppt. I'll drop it some more when I add the 8th GB and strawberry towers, plus a couple of small GBs for tomatoes.

Despite the large volume of slightly acid water I've added, the pH ony dipped slightly for a while, showing how well the shell grit's buffering action is. The water has been fairly murky for a few days due to the new GB media, I could only see about half way to the bottom of the FT, but today I can see right down again as the water clears up.
I've added a 2nd SLO, so now have side by side 40 and 50mm SLOs, which easily keep up with the higher flow rates of water returning from 7GBs.

I also have my new pump, but have not yet had the time to install it, but plan to sometime soon.

I sold another 5 bunches of chard at the organic markets on Saturday



Yesterday we ran a strawbale rendering workshop here (it's the new house for the chooks), and of course everyone was interested in the AP system, and some of the children had a go at feeding the trout, although a few pellets were spead rather wide of the tank by one of the little ones. Everyone seemed very impressed by the plants in the GBs. One woman told me of her attempt at AP a year or 2 ago, all the fish died after 2 or 3 weeks, probably due to the system water being collected from a zincalume roof.

How things looked late yesterday- plants moved around a bit since the last pic I posted, newly planted seedlings and lots of chard harvested, and a cauliflower (plus others out of view) ready to be picked. The plants didn't show any signs of transplant shock, despite quite a few roots being broken off in the move, even the wheat, which I thought would suffer.

I think I've confused some of my fish by reversing the flow rotation direction in the FT a few days ago. Some of them figured out they need to go in the opposite direction to stay in about the same place against the flow, but others continue in the same direction, going around and around the tank. They do manage to avoid colliding though

That's like asking a kid to run the other way after halftime in their first soccer game....

Winter continues to be quite warm, with just an occasional cold day, so the water temperatures have been pretty good for the trout. The temperature buffering effect of buried tanks means the water temp stays up and they continue to eat well, in the range of 75-95g of 3mm pellets each day. I ran the water heating circulation pump most of yesterday, which was sunny, and perhaps got the water temp up half a degree over what it would have otherwise been. The slope of the water temp graph is certainly steeper than on other days when I didnt run it, and that's just with about 20m of poly in the sun. With the temperature forecast to be in the low-mid 20s for the next week, I think it wont be long before I will consider doing a bit of cooling, at least to test it out before the air temps get into the high 20s.
A little bit of rain added a couple of hundred litres of water to the system a few days ago, and in the past couple of days I have drained out a fair bit more water into a now nearly full 3000l tank, which I've positioned below the AP system to collect the water for later use on blackberries and fruit trees lower down the slope. I've made it easy to do- just swapping over the pipe to a fitting with pipe connected to the tank- 15 sec to do a changeover, and it collects the water returning from 3 GBs, which normally goes to the FT. With all the new water going in at pH 6.75 I decided to add 50ml of KOH 50% solution this morning to get some Potassium into the system, before more Calcium was released from the dissolving shell grit buffering action. I probably should have added it over a period of 30 mins rather than 1 minute, as the ST water ph went into the low 8s initially, but with the addition of more water to the ST, the water returning from the GBs was pH ~7.5 for a while and the FT didnt go above about pH 7.35, and was at pH 7.26 when I checked a little while ago, only 0.13 above what it was earlier today before any water swapping or alkali additions.



We've eatsn another cauli, with more ready to pick now, and sold another 4 bunches of chard at the organic markets on Saturday

At the moment I'm welding up another GB support, which will be shorter than the rest and positioned near the FT and ST, outside the greenhouse which has the other 7GBs. I'll put 3 tomatoes in, plus plant some pumpkin and melon seeds, so the vines can grow down the slope below the AP system. I'll weld up a steel support frame to take a big shade cloth bag, a bit like the ones I use on my fruit trees, to keep fruit fly and caterpillars at bay, and to help support the tomatoes when they get huge.

Nice System Have enjoyed reading the thread and looking at the great pics and graphs. Top work!

I was wondering whether you have considered using a pool cover (bubble wrap or insulated foam) in your FT and ST to conserve more of the heat you generate? I run a local pool and once we installed our new pool covers the heating cost dropped quickly and the temp regulated.

Obviously you need to allow openings for feeding, aeration and plumbing.

Having such a big open system seems to me like you may save some heat by covering the surface of your tanks with some form of insulation.

I myself plan to have rafts on my FT (IBC 1600L system). It also utilizes more grow space.