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Aquaponic system issues - General ebb & flow questions and high pH issues

Hello,

 

So my first attempt at an aquaponics setup has been an excellent example of how not grow plants or fish. I'm a complete noob. 

 

My ebb and flow setup has a 55 gallon drum (fish tank) that drains into a 12 inch deep 3 foot diameter grow bed.  The grow bed then drains into a sump.  I have a timer that turns on a pump that pulls from the sump up to the fish tank and process begins again.  The fish tank always has 40 gallons of water until the pump starts. The fish tank drains at about the 40 gallon mark.

 

My first question is about the fish waste. Is it a problem to not have a pump at the bottom of the fish tank or not having the drain at the bottom of the fish tank? I know many systems have the pump at the bottom of the fish tank and I was wondering if having the 55 gallon drum drain at about the 40 gallon line doesn't get enough waste out of the tank.

 

I've read some guides and listened in on a few webinars, but I'm still unsure how often the timer should pump water through a system. Most of the information is very general and doesn't offer an example from which I could at least calculate a rough estimate for my system.

 

Finally, the pH of the system is quite high. It sits at 8.2 and will not budge. I've tired using both elemental sulfur and lemon juice. Both would dip the pH for about a day and it would then bounce back. So I'm concerned my media is buffering to keep the pH high.  I'm using well water that tests at about 8 (I am not using our house softened water). I'm using red lava rock (washed before using) and some pea gravel for the top layer to save my hands some grief.

 

Any tips or a link to a guide with some more concrete information would be appreciated.

 

Here is an image of the setup. I have changed the media a little since this photo.

 

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The drift wood trick is common in Aquarium culture which is also totally dependent on bio-filtration.  These water softening tricks probably could help in situations where it is just the hard source water causing the problem but they won't be sufficient in dealing with limestone media.

Hello fellow enthusiasts~

I am having issues with high pH levels as well.  I am operating two different media based flood and drain systems in Boulder, CO and have talked with Sylvia Bernstein about my issues extensively and we have not figured it out yet.  Both systems are approximately 8 months old and both systems pH have settled at 8.0. 

After the systems had initially cycled I tried to adjust the Ph levels using most of the methods discussed here (I currently have a piece of driftwood floating in my home system).  After studying aquaponics more I decided that I really wanted the systems to lower their pH naturally or at least find a more permaculture way of going about it.

In my home system (one of Sylvia's AquaBundance units with hydroton) I currently have two varieties of goldfish (9 total).  In the other system (a bath tub system with hydroton set up using Murray H's instructions) at Naropa University I have 6 mature Tilapia.  I have been to several trainings and my system issues have stumped everyone.  My water parameters have settled in both systems at approx: 0 to 0.25 ammonia, 0 Nitirites, pH @ 8, Nitrates at 80 to 100ppm. The plants have never done as well as they could have in either system and I have attributed much, but not all of this to nutrient lockout, then plant weakening which then of course leads to bugs.  The bath tub system is in a greenhouse and the AquaBundance system has spent the last few months outdoors (it goes in a sun room for the Colorado winters).

 

I am using city water to refill both systems, which I let sit for at least 24 hours in order to de-chlorinate and I pretty much always refill less than 10%.  The pH in both city water sources comes out at 8.0 so that is definitely part of the problem, but I seem to have the opposite issue with pH from almost everyone else in AP.  Both systems have some specific aquarium gravel that is pH neutral and no limestone or concrete.

 

Any ideas are appreciated~

DT

Hi Dan,

Your source water and top up water is at 8ppm PH. The top up water will buffer the declining PH and forever keep it at this 8ppm mark. If your water is high in Carbonates it becomes a strong buffer in the system, the only way around this to me is to change the source water or somehow find a way to reduce evaporation and less frequent top ups. Ap will decline PH levels over time but not if we outrun the acid produced by bacteria through constant buffering. I just took a look at your bathtub system. You seem to have 800 gallons of water to that one bathtub, add some more beds! You can up this to say 1600 gal media? If you increase nitrification capacity for the same volume of water PH should start coming down.

Hello Harold -

Thank you for your reply. We have discussed rainwater harvesting systems in the past and they are probably in our future. It is frustrating however to have to add yet another element to the sytems. I was lured initially into AP by thinking it was such a simple and sustainable way to grow fish and food symbiotically. After a year of experience in running systems and attending different trainings across the country (3 commercial aquaponics trainings and another workshop/training/conference)  I no longer feel it is quite so simple or as sustainable as it could/should be.  I have also come to the conclusion that the whole field of aquaponics is still VERY experimental and site specific.

As for the greenhouse bath tub system, it was an interesting design challenge.  The bath tub for the fish tank actually floats (with a few pieces of rope for back up) beneath the grow tank in the 800 gallon tank.  This actually keeps the fish tank water separate from the larger tank, so we actually are only dealing with approximately 60 gallons of water. We share the greenhouse with the Naropa University community and it is 90 percent soil based gardening with us tucked into the tank back in the corner - for now ;-)

 


Harold Sukhbir said:

Hi Dan,

Your source water and top up water is at 8ppm PH. The top up water will buffer the declining PH and forever keep it at this 8ppm mark. If your water is high in Carbonates it becomes a strong buffer in the system, the only way around this to me is to change the source water or somehow find a way to reduce evaporation and less frequent top ups. Ap will decline PH levels over time but not if we outrun the acid produced by bacteria through constant buffering. I just took a look at your bathtub system. You seem to have 800 gallons of water to that one bathtub, add some more beds! You can up this to say 1600 gal media? If you increase nitrification capacity for the same volume of water PH should start coming down.

And just to add one more element to Dan's pH mystery, I am on exactly the same municipal water supply and I don't have this problem at all.  My pH has been pretty stable at 6.8 - 7.0 with only rare (maybe one a year) adjustments.

Hi Sylvia,

Was reading a post recently involving TC and a close neighbor having registered different PH's from city water, so even though you are close there is a possibility of different preparation of the water from the same source.Sylvia, you sure are fortunate to have a stable PH at 7ppm, makes people like me and Dan no doubt envious.

 

HI Dan: 

AP has a whole host of limiting factors in AP and they are indeed challenges for the operator influenced by them. What I have gathered from the community on this Forum is, I believe, people readily accept these hurdles because AP appeals to their drive for conservation, and may be a small price to pay for their contribution to the good of this planet. Feelings such as these can easily over shadow any bumps in the road albeit mountains! If practicality/economics were the main considerations many of us(including myself) probably would not continue AP discipline and would have migrated to Hydroponics or others by now. Like everything else its the intentions/goals of the individual which determine the outcome.

To have persisted for 8 months is commendable( I would have most probably given up depressed by now).. It shows your level of commitment to this project. I suggest you establish the rain water system, its relatively inexpensive, and prove that you can make this work, and get the "joy" of seeing your young puppys grow up and make it to the dinner plate!

If after this, you want to continue or not will of course be a decision for you alone to make. Good Luck.

Sylvia Bernstein said:

And just to add one more element to Dan's pH mystery, I am on exactly the same municipal water supply and I don't have this problem at all.  My pH has been pretty stable at 6.8 - 7.0 with only rare (maybe one a year) adjustments.

Hay Harold,


Actually I'm on well water and so were some of the others around here in FL with the drastically different pH and buffering capacity.

And It is the buffering capacity that is causing you issues there Dan.  I suppose it is possible that even from the same source of city water one person may get more of the buffering capacity delivered than another location but it does seem a bit odd.

I can tell you that I have several different systems and each has a different pH characteristic.

The big system of course has shells as about 40% of it's media so I don't expect that system to ever really have a low pH, the shells buffer to 7.6 which is definitely better than 8.

The 300 gallon system I avoided the shells so that system I've found during the rainy season the pH will drop if I have a heavy fish load but if I'm constantly having to top up with my well water (pH of between 8-8.4 after outgassing) that system will hold a pH of around 7.6.

The Tower system with inert media and rain water collection needs frequent pH monitoring as that one will drop below 6 and give me ammonia spikes if I don't keep adding small amounts of buffer.

 

Some people will use RO water for at least some of their top up water to avoid having too much calcium carbonate in their system messing with pH and nutrient uptake.  Since I live in a rainy climate, rain water collection works for me in any systems where the media is not affecting the pH.

 

Harold Sukhbir said:

Hi Sylvia,

Was reading a post recently involving TC and a close neighbor having registered different PH's from city water, so even though you are close there is a possibility of different preparation of the water from the same source.Sylvia, you sure are fortunate to have a stable PH at 7ppm, makes people like me and Dan no doubt envious.

Good Evening,

 

Thanks for all the input.  We might end up with a RO unit and then install a rain water harvesting system down the road which the RO unit can then be a back-up for when we have dry periods.

 

TC- what have you had the best luck growing in your 7.6 pH system?  Does it tend to get buggier?

 

If we get a RO unit should I just start topping off with it - or should I do more of a water change to get in front of the buffering capacity?

Watercress grows great in the high pH ap during the cool season.  Bananas grew great in the heat but they are beasts.

Many other things struggle a little more with some pests or just iron deficiency but I still grow tomatoes and okra and beans and peppers despite the pests.

 

Should you water change or just top off with RO or rain water.  Depends on how much buffering capacity you have.  Might start out just topping off and see if the pH comes down much in a few weeks.  If you are more impatient you might do a 10-30% water change and see what sort of effect it seems to have.  Beware, I've switched systems over to rain water top up and have had to monitor pH more closely and been adding potassium bicarbonate and shell grit to them regularly now if the pH is staying too low though I suppose it is easy enough to do a top up with well water on occasion to get some buffing back.

Hi Dan,

Glad to see you hanging in with this!. RO is a great suggestion, gradual changes works best for AP. Large water changes are usually done in cases of emergency only, you want to avoid any shock to the bacteria, fish and even plants in the system as much as possible as this can weaken the overall immunity and leave us prone to attacks.

Hello, I have used Peat and wood to "try" to lower PH. When I used the peat - in a 100 gallon tank, my goldfish started dying off. Then I tried adding wood for lowering PH as well as to make it nicer for the fish. Big mistake, the wood I had used was a completely dried out vine type trunk that was cut down 2 years ago -not purchased drift wood. Unfortunately I went on vacation and all my fish died. The wood had emitted some type of fungus - it was strange, yet I am positive that this did it. It was a very sad expensive day. I would be very careful. Hope this helps.

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