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I have a Chop 2 system running for about 18 months and is been working great but lately I have to add chelated iron to keep the ph around 7 if not it drops to PH 5. I have to do this every 3 or 4 weeks. Is this normal for a stablished system.

My system is made of 3 grow beds (about 100 gallons each), a 100 gallon sump and the size of my  fish tank is about 300 gallons. I have around 60 tilapias around 6" average. I have air pumps running in the fish tank and I do have plants in all the grow beds. I added worms yesterday  in the growbeds hopefully to keep my growbeds more healthy.

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Are you adding anything else to your system???

What "chelated iron" product are you using?

There's absolutely no way that "chelated iron".... will buffer your pH.... certainly not from pH 5... to 7.....

And why are you allowing your pH to drop to pH 5.. in the first place....

Below a pH of about 5.5.... your nitrifying bacterial colony will be shutting down rapidly...

ELisamuel,

 Did you mean to say you were adding something else rather than chelated iron?

I would not expect chelated iron to raise the pH.

Calcium carbonate or potassium bicarbonate could raise the pH

Calcium or potassium hydroxide would raise the pH.

Well water could easily raise the pH if your well water is anything like mine.

pH dropping is generally a sign of the bacteria using up the carbonate or alkalinity which is quite natural and why we usually add things like calcium carbonate and potassium bi-carbonate.

While a system with a very stable low pH might be possible, it would be necessary to keep the pH quite stable for it to function.  In systems where the pH suddenly drops there is often an associated ammonia spike as the bacteria struggles.

Ive noticed that heavily stocked systems where the bio-filter is hard pressed to keep up with the load seem to be more likely to have the pH dropping stability issues more than a system with more bio-filter capacity but the same amount of fish/fish feed.

How big is your fish load?  What do your other water tests say?  How many fish?  How big?  How much grow bed?

I am sorry about the confusion, I've just got home from work and checked the bag and it's called Hydrated Lime. Please disregard the chelated iron story.

My system is made of 3 grow beds (about 100 gallons each), a 100 gallon sump and the size of my  fish tank is about 300 gallons.I gave away about 40 tilapias 6" last week to a friend that is starting a system. I currently have around 60-80 tilapias around 6" average.  I'm starting to think that I have too many fishes in my system. The water is crystal clear and the fishes looked happy. The only test I have done is the PH.

What other tests should I be checking?
 
TCLynx said:

ELisamuel,

 Did you mean to say you were adding something else rather than chelated iron?

I would not expect chelated iron to raise the pH.

Calcium carbonate or potassium bicarbonate could raise the pH

Calcium or potassium hydroxide would raise the pH.

Well water could easily raise the pH if your well water is anything like mine.

pH dropping is generally a sign of the bacteria using up the carbonate or alkalinity which is quite natural and why we usually add things like calcium carbonate and potassium bi-carbonate.

While a system with a very stable low pH might be possible, it would be necessary to keep the pH quite stable for it to function.  In systems where the pH suddenly drops there is often an associated ammonia spike as the bacteria struggles.

Ive noticed that heavily stocked systems where the bio-filter is hard pressed to keep up with the load seem to be more likely to have the pH dropping stability issues more than a system with more bio-filter capacity but the same amount of fish/fish feed.

How big is your fish load?  What do your other water tests say?  How many fish?  How big?  How much grow bed?

Sorry, I meant to say Hydrated Lime instead of chelated iron. 
 
RupertofOZ said:

Are you adding anything else to your system???

What "chelated iron" product are you using?

There's absolutely no way that "chelated iron".... will buffer your pH.... certainly not from pH 5... to 7.....

And why are you allowing your pH to drop to pH 5.. in the first place....

Below a pH of about 5.5.... your nitrifying bacterial colony will be shutting down rapidly...

That makes more sense...

I'd suggest you monitor your pH... more than every "3 or 4 weeks"...

 

And add a little each week to keep your pH around 6.2-6.6....

Alternate between a Calcium & Potassium buffer each week...

And yes... the pH drop is entirely normal....

 

And yes... you did the right thing giving away 40 Tilapia...

 

You were overstocked...

 

What on earth made you stock 120 growing fish in 300 gallons???

I did a couple of more tests:

Ph is now at 7 after adding Hidrated lime a couple of days ago

Nitrate is 80 on the chart

By the way.. if you didn't know... hydrated lime... is Calcium Hydroxide... (see TCLs post above)

They kept breeding like crazy in my tank, I may need to add another type of fish to help me control the population...lol
 
RupertofOZ said:

What on earth made you stock 120 growing fish in 300 gallons???

Regular testing of

pH

Ammonia

Nitrite

Nitrate

are the normal tests for backyard aquaponics

water testing

Yes too many fish will overload your bio-filter and tend to bring the pH down more.  Try to keep it as stable as possible.  Testing pH every 2-4 days in a very heavily stocked system is reasonable if your pH tends to drop often.

I also have a Chopp II system and Tilapia. I plan to add more grow beds to keep up with the fish waste. Until then I have added a swirl filter so I can drain off some extra fish waste to use on our square foot garden beds. This has made my water numbers more stable and has keep my three beds from being over loaded. I top off my system with well water to buffer up PH and I have a overflow drain that diverts the excess to other plants that I have in the ground. 

I have been trying to come up with a swirl filter the last few days, do you think is possible to do it with a 5 gallon bucket or a 5 gallon water jug? do you have a picture of your swirl filter so I can get an idea how to do it?

Unfortunately swirl filters or settling tanks need to be sized according to flow rates.  You need the water to stay resident in the settling tank for a certain amount of time to actually let the solids settle out so I fear a 5 gallon bucket is probably not going to be an adequate size to handle settling out much solids since to settle out 50% of the solids you probably need at least a 20 minute resident time for the water so  5 gallon bucket would probably only suite about 15 gallons per hour of flow?  I'm not all that sure here since I've really never used settling tanks in my systems.  There are online calculators that could probably help you here but I don't know them off the top of my head.

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