PH low...

[wh33t]

I can't seem to get my PH to stabilize above 6.0 anymore. In my previous experiences with Aquaponics my PH usually hovered around 6.2 but this time around it appears to be around 5.0, sometimes as low as 4.6. I just recently installed a heavy particulate filter which is essentially a rubbermaid tote filled with 3/4 gravel from my driveway (it was cleaned of course). The water is pumped into the rock bed and the flow-outs are higher up, so my theory is that the heavy particles will get stuck in the rock and also sink to the bottom while the cleaned water will flow back into the flood table. Anyhow, the water has cleaned up a lot but there is still quite a bit of heavy fish waste and leftover food sitting in the flood table. Is this the reason my PH stays so low?

Is there any other reason besides the accumulation of solid waste that could be causing the low PH?

[keith_r]

add a bag of shell grit... this will slowly bring the ph up..
if there's left over food, you're overfeeding.. lots of fish waste still in the tank, you're under filtered..
how big is are you ft and gb's?
how many fish and how much are you feeding?

[Oliver]

I have found that a pH below 6.6 retards bacteria growth and function, as does low dissolve oxygen. By keeping the pH between 6.7 and 7.3 on the outside helps keep the system operating at its best. By doing so, I have found that not only does the ammonia and nitrite levels remain low, but the heterotrophic bacteria seem to do a better job in mineralizing the fish waste solids. If I let the pH get down around 6.5 or lower, the fish tank water starts turning yellow, fish waste solids accumulate in the bottom of the tank and the chemistry is less than ideal.

According to the folks at UVI, the best way to keep the pH up is to add Potassium Hydroxide (KOH) and Calcium Oxide (lime) to the water on an alternating basis. Due to the high calcium in our water, I have yet to add the lime but I do add the Potassium Hydroxide on a weekly basis. If you add Calcium Oxide it will combine with the water to produce Calcium Hydroxide. Both the Potassium and Calcium Hydroxides are bases, which will raise your pH. Be sure to mix them with lots of water prior to adding them to your tank and go slowly so as not to harm your fish.

Potassium Hydroxide can be purchased at you local Hydroponics store as pH-UP. Be sure to look on the label as there are pH-UP products that contain other chemicals. Don't use them. In concentrated form, it can be rather nasty to handle so use gloves when mixing and rinse the outside of the container before putting away for the next use. Lime powder can be purchased at Home Depot in large bags. I haven't used the lime I purchased yet, so I can not vouch for its safety.

Oliver

[keith_r]

just don't change it to fast, as that can kill fish..
from what i found, try to limit changes to .2 at a time

[wh33t]

add a bag of shell grit... this will slowly bring the ph up..
if there's left over food, you're overfeeding.. lots of fish waste still in the tank, you're under filtered..
how big is are you ft and gb's?
how many fish and how much are you feeding?

I actually have a bag of shell grit for my back yard chickens. I also have a lot of their egg shells because I know I can add those into the system as well but I didn't want to just add something to fix the PH. I actually have PH up and a very nice PH meter but I thought Aquaponics was all about balancing the system out.

So clearly I'm under filtering, I've got 3/4 inch gravel in my tote but perhaps I need to add some of the bulk filter material. I've seen people building huge bio filters for ponds using that foam pad stuff but I'm not sure where to get it or what exactly it is.

I have 84 fish (last time I counted, I haven't seen any dead yet) in a 90 gallon system. The flood table takes about 45 gallons to fill up. I'm not sure if I'm over feeding or not as the solid waste could be either food or fish waste but I highly doubt it's food as I never see any left over food when I feed them, they are hungry basically every 5 minutes.

I feed them a cap full of the small sinking pellets maybe 2 times a day, sometimes 3 if some family comes over to check it out and wants to feed them. The cap full I am speaking of the cap of the container. Maybe 2 inches in diameter and when I say a cap full I just mean enough so that I can't see the bottom of the cap. I don't fill the whole cap up. I figure it's probably 200-250 pellets. Enough for each fish to eat 1-3 is what I was shooting for and maybe a few extra for extra large goldfish I have in there.

[keith_r]

what kind of fish? that is definitely over-stocked!
goldfish will grow.. for every 100 gallons of growbed, you can "grow out" about 25lbs of fish..when they get to 25lbs, you're really pushing a small system.., even when it is "mature"
look in "big al's" system thread for a bucket filter idea.. maybe add a couple of these, using 5 gallon pail, some scrubby pads and egg crate material..
if the feed is "floating" feed, remove what isn't eaten after 15 minutes and adjust next feed accordingly..
aquaponics is a "balance", but the natural nitrification process will bring system ph down unless you have something to buffer.. some folks use hydrated lime, but again, be careful making any sudden/big ph changes.. that's why i like shell grit.. it should slowly buffer the system up to around 7.2 to 7.4.. which has been working for me very nicely so far..

[wh33t]

what kind of fish? that is definitely over-stocked!
goldfish will grow.. for every 100 gallons of growbed, you can "grow out" about 25lbs of fish..when they get to 25lbs, you're really pushing a small system.., even when it is "mature"
look in "big al's" system thread for a bucket filter idea.. maybe add a couple of these, using 5 gallon pail, some scrubby pads and egg crate material..
if the feed is "floating" feed, remove what isn't eaten after 15 minutes and adjust next feed accordingly..
aquaponics is a "balance", but the natural nitrification process will bring system ph down unless you have something to buffer.. some folks use hydrated lime, but again, be careful making any sudden/big ph changes.. that's why i like shell grit.. it should slowly buffer the system up to around 7.2 to 7.4.. which has been working for me very nicely so far..

But my goldies are so small right now. I can't imagine how that can be over stocked. There is no where near 25lbs of goldfish mass in the water. Maybe 5 pounds right now, 10 max. I'm going to try that shell grit thing because I have some available but what scrubby pads am I wanting to use, some of them are surely made of toxic materials? I'm not sure of this egg create material you speak of. Are you referring to the polystyrene containers that they sometimes come in?

I'll check out Big Als system.

Edit: I have no idea where Big Als thread is. Would you mind linking it to me or telling me where I can find it.

[Basil1]

You can use the nylon scrubbies for bio filter. Quilt batting that you get at a craft store makes a very good mechanical filter but plugs quickly. Last pond I used a 32 gallon rubbermaid trash can. Inside was a plastic tall clothes hamper on 4 inch pvc legs. Inside were a couple hundred scrubbies. Inverted the hamper lid and put a piece of cut to fit ac filter material on it. Water pumped in thru the lid and out a 4 way on to the filter. Gravity fed down and out a pipe about 4 inches up.

[stucco]

R u usin rain water for your top up water?

[Oliver]

You can use the nylon scrubbies for bio filter. Quilt batting that you get at a craft store makes a very good mechanical filter but plugs quickly. Last pond I used a 32 gallon rubbermaid trash can. Inside was a plastic tall clothes hamper on 4 inch pvc legs. Inside were a couple hundred scrubbies. Inverted the hamper lid and put a piece of cut to fit ac filter material on it. Water pumped in thru the lid and out a 4 way on to the filter. Gravity fed down and out a pipe about 4 inches up.

I know that people use nylon scrubbies for bio-filter material, but I have a concern that I have not checked into, so I am throwing it out here.

Nylon is a high dielectric material. My concern is that autotrophic bacteria supposedly attache themselves to substrates and I am wondering if the high dielectric of nylon might preclude them from making that attachment. Again, I'm not saying they won't but for some reason I sense a need to question this.

Just a gut level feeling, which probably means I read somewhere in the distant past about organisms attaching themselves to synthetic material.

Wish I could recall it better. Guess I will do a search on this when I get the time, whenever that is.

I'm more into converting the solid and liquid fish waste than I am "filtering" it out of the flow.

Oliver