Hi Guys

I am new just converted my pool to a pond.

it’s been 6 months now and i have about 25 koi inside.

Setup:
28000l
Flow in order no bottom drain (still to install)
0.75 Speck Pump cal flow is 200l/m
Multicyclone
P23 Sand filter 5mm sand
55w UV
Bio filter 50 liter (735 bio balls - 24000l pond)
Biowater fall 200L drum with plastic shaving and lava rock


I have a problem with my filter not cleaning and blocking. i have to back wash for 20sec and the it work for about 6-8 hour before next back wash.

I have now bypassed the P23 sand filter.

Also opened it up and found some red worms and snails.


Also have algi building up.

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Hi Sealan,

Think the first thing you should do is remove all the sand from the sand filter and take the plastic fingers and make the grooves in between them bigger. This will help greatly with the sandfilter not blocking up.

Altho with that size sand you shouldn't really be cloging up. DO you have a weir basket on your pump or does the crap from the pond go straight into the sand filter?

Red worms and snails are fine, snails never checked in a sand filte rbfore but know the blood worms are fine

The holes on the pool sand filters are much smaller than on koi sand filters.
Drill bigger holes as Cliff suggested and add normal builders gravel (7mm) to your 5 mm sand.

Hi Sealan

I have a sand filter with +- 7 mm stones in, Normal backwashing does not clean the filter. Backwashing and manual stirring of stones helps a bit. But you will not get all that sh-t out until you have drained your whole pond.

I Backwash manually open filter ones a week and remove all the sand ones a mouth and clean it manually. You can not believe all the sh-t that comes out.

DAVID wrote:

you will not get all that sh-t out until you have drained your whole pond.

Would not drain the pond. You will loose all the maturity that has build up already.

You have a new pond and the algae build up is normal in the first year. Everything will come into balance in due course. The algae problem will also get better as it gets colder.

However, because you do not have a bottom drain, you will have to vacuum your pond regularly. The .75 pump should be able to do the job. Put the filter on waste when you vacuum the bottom.

Hi thanks for the info.

I have now run the pool for 24h with no sand filter, my Multicyclone picked up a lot of dirt was 1/4 full.

But now i have white foam on top my biowater fall, and some in the pond.

Would it be good to use an Aligi control product any recommendations

Hi Sealan

The one sand filter is going to struggle to keep your system clean and I think you should add another bio filter unless that one has alfagrog inside it.

You can add pond clear but that is a short term solution.

I do not see your U V light? for 28000lt you probably need 2x30 Watt UV's
and they should be installed in a split stream not in tandem.

You will have to unpack that sandfilter now and clean it properly and until your pond is clear you must do a stir and backwash every 2 days.
The foam is not a problem Did you put salt in if so then you will have a bit of foam.
There is a new sandfilter finger on the market that I would recomend the slots is only in the bottom half.

Very nice koi pond I like it

Hi Thanks again for the info.

yes i do have a UV 55W not in the pic.

could one revers the flow on the sand filter.

If the water enters on top flows through the sand and into the fingers, think that could work?

Also has an seen Ultima II 4,000 Filter ?

I was thinking of replacing the sand with the plastic media, and flow from top down the modify the finger to act like jets to spin the media on backwash

Hi Sealan

Just another thought. Many koi keepers in East London dont use their Uv lights abd use Barley straw instead. I have seen a 75000 liter green water pond go chrystal clear within two ans a half weeks The temperature was then 27c. It cost him only R120.00 and it works for 6 months. Another idea is to put zeolite in the sand filter naturally it should be placed after the Bio filter but it takes all the remaining ammonia out of the water which returns to the pond. I use zeolite and it works well.

Regards

Roy

Hi Sealan

No you cannot reverse the flow of your sandfilter but the way you describe is the way it works from top to bottom.
If you have a UV and your water go's green the UV globe is out of service and it should be replaced.

Hi i think that the UV could be the suspect.

I have had it on for 7 months only had a problem in the last month.

I noticed that it runs even if the motor is off.

Is there a way to check, i know it is on as i can see the white ring on the side at nigth

Hi Sealan

In my opinion 1 x 55 watt UV is not enough, my pond is 27000 and I had to had another 55w UV.your pond is in the sun most of the time so I suggest 2 x 55w Uv as well more filtration, get yourself a 1000l
Square tank they go for about R700.00 clean and fit some brushers or any other cleaning media

Hi Sealan

No doubt your Uv is gone, the only test is you see your water going green then you know it needs replacement they only last 10 to 12 months if you use them all the time. and I agree with Joe you are going to have to add another one but not in tandem you must split the flow.

If you're running sand filters on that size pond you'll need at least 3 of them. As mentioned before here, if you don't open the filter and stir the sand while backwashing at least once a week it will cause all sorts of trouble and your media will harden and clog up quickly.

The best advice I can give is to replace the sand in your current filter and then, if possible add 2 more sand filters. Add normal small 1.1mm pool sand to the last filter.

If I can comment about the UV's..... One of my new ponds is 14500l. The water went green in a matter of 24hrs. I then added a 15w UV and my water cleared in 1 week. I don't think that you need an extra UV. Also make sure that your UV is the last contact point for water before it returns to the pond. Pump - Filters - UV - Pond. I found that if a UV is before the filters, you need to replace the bulb sooner as there's more "rubbish" that runs through the UV.