~ CAN'T GROW waterplants in this POND ?!?!? ( HELP )

[spanishleprachaun]

    Hey all --- went to go see a fellow ponder down here in warm San antonio, Tx,...
She has a pool she converted into a pond.   The new depth is on avg 20inches deep.  Full sun,... the water is not terrible warm at all.
The pond is a huge bowl of PEA SOUP with single cell phytoplankton algae. 

She has hundreds of minnows and 12 koi.   Nothing in the way of plants lasts long in this pond.  They just DIE.

Not water hyacinth, water lettuce, umbrella palm, reed, lily or even the wild DUCKWEED ?!?!?!

No run off from weird stuff in lawn or anywhere else.

What would be going on here ?

dazed and confused,
carlos

[gander]

Sounds like the pea soup is getting all of the nitrogen and other fertilizers. Sounds like it does not need any Koi in it either. Is she planting her lilies in soil and using plant tabs or something to fertilize them with? I do know that water lettuce and WH sometimes are hard to start in a full sun pond. Once they get going though look out.

[Desertponder]

I lived in a place once where I could not get water plants to grow either. The ph of the water there was extremely high. I did not have a lot of algae because it really didn't grow either. I had crystal clear ponds at that house but couldn't get plants to grow. I would be inclined to suspect her water. Muriate of Potash seemed to help. I could get iris, cattails, some other rush type plants and lilies to grow but no floaters at all. Lettuce, hyacinths etc. would just turn brown or go to mush and die, almost like they were getting burned. I haven't had that problem since we moved away from there and we now have a different water source.
Also, could there be any residual chemicals from the pool that could be causing problems?

[tranquility]

Also would make sure she doesn't have salt in the pond...that is the main thing I find when people are having trouble growing plants....
Lawanna

[Kittyzee]

I was wondering about leaching chemicals from the pool material (cement?), into the water.  20 inches doesn't sound very deep for a pool and am wondering how could that water be cool--especially in the Texas area? 

[Reedman]

My guess would also be high pH.

[Jerry]

Hi Carlos. Good to see you.
One idea here. Drain the sucker and use a EDPM liner1

[spanishleprachaun]

          Thanks all for the good advice.
She has never nor does have any trace of salt in the water.
there is a 45mil edpm liner that contains this water within the shell of a pool
substrate is normal gravel and top soil --- nothing special.
water has been in the mid 66-72degrees ---- still cool enough not too boil anything

[spanishleprachaun]

  What would be a acceptable PH level for plants ?   thnks

[tranquility]

I would think if the ph was too high then not only would the plants suffer but, so would the koi...

[enzo]

I would run some basic water tests and start doing some partial water changes. Would you happen to have a photo?

[Jerry]

he does Enzo! Looks good doesn't he?