Results of an Experiment

[Griz]

I have long been interested in the effect of Rhododendron leaves on water. I have seen only a few vauge references on the 'net to using them to lower pH in aquariums, nothing definative. I'm a gardener and grow rhododendrons. They prefer acid soils so it made sense to me that they may have the ability to lower the pH of water. Peat moss is often added to the soil to help with acidity. I decided to perform an experiment and results turned out to be very interesting.

CAUTION: I have no idea (yet) as to whether rhododendron leaves are safe to use in an aquarium. Do so at your own risk! More research will need to be done.



pH and Water Hardness Experiment
================================

To compare and measure the effect of rhododendrom leaves and Fluval Granular Peat on the pH, General Hardness (GH) and Carbonate Hardness (KH) of water.

Approximately one heaping teaspoon of crushed Rhododendron leaves and one teaspoon of Fluval Granular peat were used.

Samples were mixed with 250 ml of water. Two different water samples were used. A & C was water from a dehumidifier (extremely soft). B & D was water from my aquarium (average hardness).

Water parameters were measured at the start of the experiment and at 4 hour, 8 hour and 24 hour intervals.

The containers were agitated/shaken about once every hour.

Tests were conducted using a Tetra brand liquid test kit.

--------------------------------------------------------

A & B Rhododendron Leaves
C & D Granular Peat (Fluval)

A & C Dehumidifier water
B & D Tank water


Results
=======

---------A-------B-------C-------D

0:00 hours
pH-----7.2-----7.5-----7.2-----7.5
GH-----0------10.5-----0------10.5
KH-----1.5-----6-------1.5-----6

4:00 hours
pH-----6.0-----7.0-----6.5-----7.0
GH-----0------10.5-----0------10.5
KH-----1.5-----5-------1.5-----4

8:00 hours
pH-----6.0-----6.5-----6.0-----6.8
GH-----0------10.5-----0-------7
KH-----1.5-----5-------1.5------3

24:00 hours
pH---**5.0----6.5-----5.0-----6.2
GH------0-----10.5-----0------ 5.5
KH-----1.5-----5-------0--------2


**I suspect that this reading is actually less than 5.0 due to the colour produced but that is a low as my test kit colour key shows.


Observations
============

The Rhododendron leaves tinted the water a much darker brown than the Peat. Having used the Fluval Peat for nearly a year, I know that it will definitely stain the water when placed in a hang-on-back style filter (I have an Aquaclear 200) but the peat did not stain the water much at all in this experiment, which surprised me a bit. I suspect that the reason is that there was no water flow in the containers used.

Conclusions
========

Rhododendron leaves do in fact have an ability to lower pH that seems to rival the ability of granular peat.

Rhododendron leaved do not seem to have the same ability to lower GH and KH the way peat does.

 

[SarahBravo]

Ummmm, aren't rhododendrons poisonous?? On the web it says poisonous to pets and people if there is sufficient exposure - given the size difference with fish would it make your water toxic?

Cool experiment tho'!

Edited for spelling rodo.....rohdo.....ummmm those plants

 

[Griz]

Thans exactly what I am wondering. Any botanists out there?

 

[The-Wolf]

Very interesting experiment; two questions though..
did you used brown leaf(dead) or green leaf (live)?
do you think that water temp would have any effect on the results; IE warmer water = more lowering; colder water = less or vice versa?

edited for punctuation

 

[annka5]

Unfortunately, rhodedundrons are definitely poisonous. I think the experiment is a really good idea, but could you use othr leaves, similar (maybe camellia, but am not sure if they would also be poisonous...)

 

[Griz]

I used completely dried brown leaves. These were set out in the sun for a few days to make sure that they completely dry. Never thought of the temperature angle but it does make sense.

I've done a bit of research on Rhodos and it seems that the nectar is poisonous and to a lesser extent, the leaves. I wonder though if a completely dried leaf would still be toxic. Also, just because something is dangerous to a mammal, it might not be harmful to a fish. Got to look into this some more.

I was quite surprised at how well this worked. I did consider trying spruce needles which are often used to acidify soil but I questioned if they would be any good for fish. It would likely work though, so I'll probably give it a try just to see.