[Wet Thumb Forum]-Water Change in 55 gal with Pots

[dwalstad]

Dear Fellow Hobbyists,

The 55 gal with potted plants that I set up in March has for the last month been showing reduced plant growth; algae is starting to grow on the glass and some of the plants. While fish are doing great, I felt it was time to take action.

I measured nitrates and they were very high, 60 ppm or higher. The problem for plants may simply be salt accumulation. This increased salinity (from nitrates, chloride, sodium, etc) may have inhibited many plants. The water hardness has not changed, probably because these ions may precipitate (much calcium will precipitate as calcium phosphate or calcium carbonate) and be removed from the water.


In any case, I changed 70% of the water.

Please realize that this tank has gone for over 6 months with the same water that I set it up with. Thus, while I advocate infrequent water changes, there are times and situations where changing the water is a good idea.

Let common sense be your guide.

[dwalstad]

Dear Fellow Hobbyists,

The 55 gal with potted plants that I set up in March has for the last month been showing reduced plant growth; algae is starting to grow on the glass and some of the plants. While fish are doing great, I felt it was time to take action.

I measured nitrates and they were very high, 60 ppm or higher. The problem for plants may simply be salt accumulation. This increased salinity (from nitrates, chloride, sodium, etc) may have inhibited many plants. The water hardness has not changed, probably because these ions may precipitate (much calcium will precipitate as calcium phosphate or calcium carbonate) and be removed from the water.


In any case, I changed 70% of the water.

Please realize that this tank has gone for over 6 months with the same water that I set it up with. Thus, while I advocate infrequent water changes, there are times and situations where changing the water is a good idea.

Let common sense be your guide.

[DataGuru]

Interesting. So you think the salt accumulation was happening because you were topping it off from evaporation? and that resulted in the plants not growing fast enough to use enough nitrAtes and the extra nitrAtes stimulated the algae growth?

Do you think you get as much denitrification with the pots as you would from a soil substrate with a gravel overlayer?

and do you have any feel for what is the maximum amount of nitrAtes that can be used up by plants/soil substrate? Is there any way to quantify that?

Betty

[Robert Hudson]

That could be a toxic level for fish could it not? Did your fish show signs of distress?

[Waterproof]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Betty:
Do you think you get as much denitrification with the pots as you would from a soil substrate with a gravel overlayer?
Betty <HR></BLOCKQUOTE>

Very good question. i myself don't think a soil substrate would be better to get more denitrification. But how about mosses or ferns that don't need any soil at all? were there some in the tank ? aquatic plants are strange things because they can feed not only with their roots but directly with their leaves too.

To Robert:
Many scientists would say a concentration of 60ppm nitrate is not very harmfull to the fish, but it's no need to wonder why they won't spawn or get bigger. fish can live in a 100ppm nitrate concentration but will stay small and won't reproduce. that's what happens in the small river flowing along my garden.

Waterproof.

[dwalstad]

I don't think nitrates themselves are toxic. As I wrote (page 62 in my book), scientists found that 400 mg/l did not affect the growth or mortality of channel catfish and large mouth bass. That doesn't surprise me. Nitrates are like the chloride ion (as in ordinary salt made up of sodium chloride). There is nothing toxic about nitrates, per se.

As to Betty's excellent questions, I do think that nitrates will accumulate more in my tank with potted plants than others with a soil layer. With a soil layer, there's just more anaerobic areas (deep in the soil layer) that denitrifying bacteria, which convert the nitrates to nitrogen gas, can do their business.

As to increasing salinity inhibiting plants, I'm looking into buying an instrument to actually measure whether the salinity is actually increasing over time. My first letter was just speculating that salinity was what was inhibiting the plant growth. I have yet to prove that.

Again, my point was that you don't have to change water twice a week to have a nice planted tank.

As to Waterproof, it is a pleasure to hear from a French hobbyist. Your English is far better than my French!

[DataGuru]

Bonnie Hale did a study on salt tolerance in pond plants... Not exactly the question you're wondering about tho (growth inhibition) with lower levels). There's a table up on her site that lists plants and how much salt (.1%-.6%)it took to kill them.

NitrAte not toxic. Interesting. I keep hearing people talk about decreased immune function, lack of spawning, flipover in goldies, etc.

Betty

[dwalstad]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Robert H:
That could be a toxic level for fish could it not? Did your fish show signs of distress? <HR></BLOCKQUOTE>

Hello Robert,

The 9 fish in this tank have always stayed healthy. They have never shown any signs of distress-- either now or before the water change.

Two of the 9 fish were "fingerlings", one inch long Orange Rainbows when I set up the tank. They have grown nicely, and the male is just starting to show some color.

Here is picture I took of fish this morning. The fish below the pair of Red Rainbows is one of the Orange Rainbows (Chilatherina fasciata). I'm guessing she may be a female and won't color up much.



What caused me to measure nitrates and change water was that my Water Sprite stopped growing. And I know that when plant growth slows down, algae will start to grow.

The website cited in Betty's letter (thank you Betty!) that Water Sprite seemed to be more sensitive than many other plants to salinity.

I've just purchased conductivity meter and will start to measure salinity in my tanks.

[Robert Hudson]

Cool! Diana, can you give us any sort of preview of what you will be speaking about at the AGA convention? I can hardly wait! I am looking forward to meeting you!

[dwalstad]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Robert H:
Cool! Diana, can you give us any sort of preview of what you will be speaking about at the AGA convention? I can hardly wait! I am looking forward to meeting you! <HR></BLOCKQUOTE>

Hello Robert,

I hope that you won't be too disappointed when we actually meet! I am not a scintillating public speaker, but I'll try my best.

My talk will be on how a planted tank is healthier to fish than an unplanted one. I will include data on how plants remove ammonia and nitrites. This information is already on your website.

In addition, I've found (via experiments) that soil processes and soil bacteria also help out...greatly in neutralizing aquarium toxins. This will be new information to many hobbyists.

My goal is to convince beginning hobbyists that keeping plants in their tank helps enormously in keeping fish healthy, reducing tank maintenance, and controlling algae.

I think that there will be plenty of time alloted for questions, which I always enjoy.

Look forward to meeting you.