Pond filter question

[Sportsman]

I have a home made pond filter which consists of 4 layers of foam and about 25cm of lava rock as the bio element.
I remove and clean the foam from time to time, but I don't disturb the lava rock as I don't want to affect the bacterial action.
Just lately the water has become murky. It is not algae it is more like suspended black matter making it dirty rather than green. The filter doesn't seem to be helping, in fact, it seems to get worse when the pump is running and settles down when you switch the pump off.
Any suggestions as to what might be causing it and what I might do about it.
I was thinking of washing out the lava rock, but don't want to disturb it if it is not necessary.
Thanks

 

[banksy]

What size and depth is the pond?
Numbers, variety and size of fish?

 

[spanky]

It's worth flushing the lava rock as it does become clogged from time to time. The good bacteria should be quite sticky, so you wont lose all the good ones as long as you dont let it all dry out for too long. For my pond I keep the lava rock in onion bags so I can lift them out from time to time and give them a quick flush as and needed (plus you can do a few each week if you want to rotate). The lava rock will clog over time if you dont clean it.



Just remember to reseed the filter afterwards. I use a handful of these



every time. I ignore the instructions since this would require huge amounts, if your filter is already running it'll just need a boost, not a complete restock.

 

[Sportsman]

Spanky, Thanks for that. I just tried running the filter without and sponge in place and the water was not getting past the lava rock properly, but was filling the bin and escaping via the overflow. That means it must be the lava rock at fault, so I will take your onion bag suggestion and clean it more regularly.
Banksy about 15' X 9' deepest 3'6" Lots of small fan tailed goldfish. I will be thinning them out for next year.
I should add that there is a fair amount of canadian pond weed and water lilies, along with another floating plant that my daughter put in. The water isn't getting a great deal of sunlight these days and there is probably quite a lot of dead rubbish building up on the bottom

 

[Trogg]

To save reseeding the lava rocks, just take a bucket of water out of the pond and give them a wash out in that, don't scrub them just wash them over using your hands and keep dunking them to wash the crud out/away after.

 

[62tucker]

Always use pond water to wash the sponges and the rock. Also if pump not running 24/7 your bacteria will die ( I think that’s right) it needs running water to survive. If it’s off for a while the water in filter will just go stagnant.and when u put pump back on all the stagnant water will go into your pond.

 

[dry nets]

Are you running a bottom drain or are you pump fed. To the filter
Air pump fed you’ve more likely got months/years of muck buildup and the fish are disturbing it off the bottom.
You’ll need to hoover it up and change some water. Probably 50%. You should be changing 10% every week.

 

[62tucker]

Dry nets knows his stuff so listen to him.
I syphon the bottom of my pond at least once a week. Maybe 3/4 time in summer. A Dustin out at a time. All old fish poo and whatever else on bottom. Better out than in. Also have pond pump up about a ft off bottom so hopefully big stuff doesn’t go in it and to filter

 

[Dave]

Clean your foams, and remove the Lava rock.
Put the lava rock in a big tub of pond water. Use a jet wash to clean the foams, then let the excess drip out.
Don't clean the Lava rock as this is where the friendly bacteria lives.
Then remove all the built up sediment from the bottom of the filter box.

Unless you've got a bottom drain on the filter box you'll have to do this occasionally to remove the build up.
Once the build up gets to or near to the level of the bottom of the vertical pipes in the filtthe water flow will start to drag it out and cause the permanent discolouration.

 

[Barbel seeker]

Had a similar problem earlier this year and tried everything to no avail so went down to the local pond shop and the lad in there is very knowledgeable but I also had the problem of a lot of foam floating about below the water return pipes, he went through a few possible causes but the thing that cured it was to renew the filter foams not wash them and a new u v bulb, he mentioned that after a year the foams do start to deteriorate and become less efficient but to change them one by one over a month or so so you don't lose all the good bacteria, anyway water back to gin clear and Pond much cleaner also he told me to cut back on the amount of food I was giving them

 

[Sportsman]

Thanks for all the replies.
I have cleaned the crud from the lava rock and returned it all to working condition. I think it is overdue for a water change, so that is next on the list of things to do.