Pond water quality dropping after converting to undergravel filter

[patrick]

I recently converted our pond filtration to an undergravel filter with bog plants to clean the water. The pond used to be a 400 gallon pond with a 15' stream with a weir at the top. My pump is a 5000gph underwater. Due to being under a treeline (bad I know) I converted it to a pond with about 18" above ground with 6X6 pressure treated lumbar with a cedar top. Using pond liner. My biggest change was to make an undergravel filter pumping water thru a 1 1/2" inch pvc to a circuit of pipe with holes thru an undergravel area that spills into the pond.

The water is more cloudy than ever before, we have lost some of our fish which never happened before. The new version is about 6 weeks old. The fish got sick after 1 month. I checked ph and it was between 8-9. I changed the water and treated with ph down till I got closer to 7.

I put a bubbler in to increase aeration. I have added the bacteria to help set up the filter media to process the nitrates.

Finally, the water seems warmer now than it used to be. The pond is now about 700 gallons, but I have no rock and gravel over the bottom. I think the black liner is absorbing more heat than when the bottom was covered.

The undergravel filter primarily has cattail and mint and is slowly establishing itself.

Any advice on using bogs and undergravel filters to filter water appreciated.

Pat

[Julles]

Hi Pat, and WELCOME to the forum!

Bog filters are supposed to be very efficient and thorough ways to filter your water.  I wonder if it has been set up properly?  A friend of mine had a bog filter, and was unhappy that it wasn't cleaning the water.  I took a look at it and - she had the PVC pipes on TOP of the gravel!  Here are a couple of tutorials on Bog Filters.

http://www.americanponders.com/forum/index.php?board=22.0

http://nelsonwatergardens.com/data/resources/other/31_Bog%20Filter%20Construction%2008%202.doc.pdf 

Was your gravel clean when you set up the system?  Is there a possibility of any chemical residue in the gravel?  Do you have plants in the pond?  Plants also aid in filtration, plus they add oxygen to the water, and shade the pond, too.

And remember that new set-ups always go through a cloudy water phase.  Maybe it just needs a little more time for everything to settle.

[Joyce]

It's not established yet. Especially since you have changed the water.
Every time you change the water, you wash away good bacteria.
If it were my pond, I'd leave it alone, absolutely no tinkering for another month.
EVERY time you tinker with your pond, you interfere with the biofiltration.

Your profile leaves us clueless to where you live so if you live in a cooler climate, that will also interfere with your biofilter establishing itself.

Takes time and patience. 

[patrick]

I knew I would set back the balance by changing the water. Just hard to watch the fish struggle with no certainty if something had gotten in the water. The kids knew  and named each fish. They would follow them around looking for food.

I wondered if PVC glue had gotten in, or if the spillway had leached something from the pressure treated wood. I took water to a fish shop and they tested for many things. Nothing.

I do have bog plants, cattail is the primary, a couple days ago I split them up and washed out the soil the garden center had in them and replanted in the gravel. I want to get some reed but have not found a source. I am in Northern Virginia.

Concerns with the setup are the waterflow with a 1 1/2" pvc, areation without the weir and warm water with a big black bottom rather than gravel covering the floor.

I will send a photo of the setup when I get home today to give an better idea of the setup. The gravel is typical pea gravel, primarily made up of quartz based rock.

Regar

[tranquility]

Well even though I'm a NO Rocks in the pond girl...I have to agree with Joyce--the system has not cycled and  IMO those magic potions in a bottle that they like to sell as bacteria aren't worth their weight in fish poo...I was told it takes about 49 days for a filter to cycle...have you tested the water--I would want to know the ammonia,nitrate,nitrites, and ph...ammonia alone will not kill your fish--but, high nitrites will cause brown blood disease....also keep in mind that the higher your ph is then the worse the nitrites will affect the fish....and just remember green water doesn't always mean bad water quality and clear water doesn't always mean good water quality..the only way to know the water quality is to test...and please stay away from the strip test kits they are in accurate and if your having problems then you need a accurate testing kit so buy a drop test kit....also--when you refilled the pond--did you use declorinator? or are you using well water? I'd also suggest alot of airation right now--those fish are stressed and all the extra O2 they will be greatly appreciated...Sorry didn't see your above post before I typed all this--but, I'll leave it just incase ...you had your water tested--I'm a bit anal about this--I would want to know exact readings--so if it were me I would buy my own testing kit($30) and test daily untill I know the pond has cycled...I've never used wood in contact my ponds but, stands to reason that the wood may have a chemical in it that is not safe for fish...
Lawanna

[Jonna]

I too would do a lot of partial water changes because I can't watch fish suffer.  If you change 25% of the water every week, you will still cycle your pond and you will give the fish a break from whatever is bad.    I have 2 bog filters here and another one working up in calif.  They have done a good job for me but I always have a pretty low fish load.  Do you have a lot of fish in the pond?  Down here I even have cichlids in my ponds with only a bog filter and they are doing fine.  Also, my PH is over 9, I can't really test it with my kit because it stops at about 9.  Usually, fish can deal with larger extremes in PH if it is stable.  I wouldn't try and lower the PH with chemicals, it won't work over time and it will stress the fish. 

I feel for you having your kids watch their fish die.  That's a tough one.  I hope you figure out what was going wrong.  It doesn't normally work like that.  Add air, do regular water changes, keep testing the water regularly... that's the advice you've gotten and I agree with it. 

[Esther]

You will not always have a black pond liner. Eventually you'll have gunk settling on it and algae growth. Mine is not black at all any more.

[miguynmkoi]

The ladies above have it right.  I wonder if it would be wise to take the fish out and put them in a good size container with air pump/filter until the water has cycled?