toxic-free materials/additives for fish breeding tank construction

[Mitker]

Hello,

We are starting the construction of our factory rain water reservoir (concrete tank).

It is aimed at keeping a safe quantity of water available all year round (we are not connected to the water distribution network) and of respectable size.

We plan to use this reservoir for fish breeding altogether, our main market being our staff and its management team .

For this reason we are looking for the best choice of materials to avoid any toxicity to be transmitted to the fishes that should sooner or later end up in our dishes.

Basically, the tank will be made of several concrete elements jointed together (this is due to technical and design constraints that can hardly be modified).

I am not concerned by the concrete in itself but by 2 extra components:

- the waterproofing additive added to the concrete mix

- the expansion joints we will have to use between the elements

Has any of you ever investigated this matter or have some expertise on this? (couldn't find clues on the forum but maybe that I didn't search the right sections)

Any information helping to select the safest products for the 2 applications above would be highly appreciated.

Our schedule is tight so that we are looking for locally available products.

Thanks in advance

Mitker

[cdmtdm]

i have found one lanko product which is suitable , however Shell has a product i think is better and will ring them tomorrow , will pm you with my results tomorrow ...

[canuckamuck]

I have used the standard water proofing additives to concrete mix, and I do not think they are a problem. In fact I think the fact that they make the concrete water proof helps to keep chemicals from leeching in from the concrete itself. However I have no science to back this up. I have four concrete tanks in which I raise fish.

All of them have the waterproofing compound in the render,and the fish seem to be doing OK with it.

However, I think that coating the concrete with a waterproof barrier that is non toxic is a very good idea. People seem to be recommending Shell's Flintkote, particularly Flintkote 3. I tried the Flintkote Super, and I am not convinced it is totally water proof, but I did the job in rainy season and there were complications with my application. Flintkote 3 may be better than the Super. The Super looks like tar but is very easy to work with.

I also coated a concrete tank with fiberglass resin (one coat) and I am very happy with the result of that. However it is more expensive and you go through brushes rapidly, as the fiberglass hardens in about 15 minutes.

[Mitker]

i have found one lanko product which is suitable , however Shell has a product i think is better and will ring them tomorrow , will pm you with my results tomorrow ...

Thanks for this, cdmtdm.

I've done some search on internet and spotted some products but few available here. Will gladly hear about Shell answer.

[Mitker]

I have used the standard water proofing additives to concrete mix, and I do not think they are a problem. In fact I think the fact that they make the concrete water proof helps to keep chemicals from leeching in from the concrete itself. However I have no science to back this up. I have four concrete tanks in which I raise fish.

All of them have the waterproofing compound in the render,and the fish seem to be doing OK with it.

However, I think that coating the concrete with a waterproof barrier that is non toxic is a very good idea. People seem to be recommending Shell's Flintkote, particularly Flintkote 3. I tried the Flintkote Super, and I am not convinced it is totally water proof, but I did the job in rainy season and there were complications with my application. Flintkote 3 may be better than the Super. The Super looks like tar but is very easy to work with.

I also coated a concrete tank with fiberglass resin (one coat) and I am very happy with the result of that. However it is more expensive and you go through brushes rapidly, as the fiberglass hardens in about 15 minutes.

You are right pointing that waterproofing might be beneficial by preventing chemical migration from the concrete core.

In Europe, I remember cement bags mentioning being free of some hazardous substance (was it chromium..?). I don't trust safety standards here and don't expect any supplier to care about such "details".

It definitely looks like Shell has something to offer.

Personally, I wouldn't go for fiberglass, first because the application itself requires powerful chemical solvents, second because the coating suffers from UV after a few years of exposure. Our reservoir will be wide-exposed and with a varying level of water.

Thanks for the info.

[canuckamuck]

From what I have been told there are also waterproofing paints, suitable for reservoirs. I have heard TOA has a version here in Thailand. So far I have not found it. Except that a friend of mine has used it and it was a nice blue. He told me to ask at TOA dealers but the ones near me say "no have".

I understand it is epoxy based. If you find it let me know.

[Mitker]

As additive to be mixed to the concrete, we spotted Sika-1 as fitting perfectly our bill (suitable for drinking water tanks) but.. not sure it is available in TH (the info comes from their Sika Egypt and our local dealer doesn't know this reference). We are trying to figure out with BKK.

http://egy.sika.com/en/solutions_products/02/02a001/02a001sa01/02a000sa01500/02a000sa01501.html

Another option is KIM from Kryton. It can be ordered from their BKK partner

http://www.kryton.com/products/krystol-internal-membrane-kim/

Being both suitable for drinking water equipments, they seem to offer the best guarantee of low-toxicity while sparing us the application of a extra layer. We may go for that.

ps: it may be necessary to let some water neutralize the high PH of the concrete first. Seen on some suppliers websites some mention of this PH being detrimental to aquatic life.

[hominoid]

got this attachment from somewhere.

also aquaculture has plastic liners for ponds- worth a try in a cement pond?

try a very small test pond with your actual material and get the water properly analyzed. personally i think you are jumping at shadows. concrete is sand gravel and cement all natural stuff which i would prefer over pond liners and chemical safety stuff. if it leaks a little so what? but test it first just allay your fears.

vkrkxo3104 Safe Seal data 08.pdf

[cdmtdm]

As additive to be mixed to the concrete, we spotted Sika-1 as fitting perfectly our bill (suitable for drinking water tanks) but.. not sure it is available in TH (the info comes from their Sika Egypt and our local dealer doesn't know this reference). We are trying to figure out with BKK.

http://egy.sika.com/en/solutions_products/02/02a001/02a001sa01/02a000sa01500/02a000sa01501.html

Another option is KIM from Kryton. It can be ordered from their BKK partner

http://www.kryton.com/products/krystol-internal-membrane-kim/

Being both suitable for drinking water equipments, they seem to offer the best guarantee of low-toxicity while sparing us the application of a extra layer. We may go for that.

ps: it may be necessary to let some water neutralize the high PH of the concrete first. Seen on some suppliers websites some mention of this PH being detrimental to aquatic life.

ok talked with Shell today , the product they sell to fish farmers here in LOS is Shell Flintkote Super , about 200 baht a kilo , approx 1 kg per sqm metre , downside is its only available in black ....can be ordered through any home pro , 100% non toxic

[Mitker]

got this attachment from somewhere.

also aquaculture has plastic liners for ponds- worth a try in a cement pond?

try a very small test pond with your actual material and get the water properly analyzed. personally i think you are jumping at shadows. concrete is sand gravel and cement all natural stuff which i would prefer over pond liners and chemical safety stuff. if it leaks a little so what? but test it first just allay your fears.

Do agree with you that concrete should be safe in its basic form but various additives are added in the process nowadays for easing its processing/workability. I think they are the real concern. Wiki mentions some.

Also we look at it the other way around: we are surrounded by fields that are sprayed on an almost daily basis with an quantity of pesticides/fertilizers/herbicides by farmers who even recognize their impact on their own health but... the yields... Our soil being a mix of clay and sand, we noted water running a couple of meter below the surface. We expect this water to carry the nice chemicals generously sprayed in the vicinity (we regularly witness the sudden crabs/fishes mortality in the nearby klongs when it's spraying time). So if our reservoir happens to be low at a given moment and the paddies inundated, we would see this underground water infiltrating our tank.

Our fishes will be the permanent filter of the water and since they are just at the lower step of our food chain, we will be the final recipient of their fine work.

[ikan]

i think you would have more chance of wind borne contamination that via underground water. you are going to be running a filtration system too i imagine?

[Pacificperson]

Concrete is safe. The facility I manage has concrete ponds that were built 33 years ago and they are the only things that are still in decent shape in the place.

One thing that the original builders did do was to use thicker walls (6 inch) and less rebar than one would expect for the ponds. This has had the advantage of reducing the spalling over the years. Many of the ponds are used for full strength salt water and we still see very little spalling. The concrete buildings on the other hand had thinner concrete and more rebar and are spalling like crazy due to the salt intrusion from the ocean spray.

Normally, one ages a concrete pond for 30 days before putting fish in it.

[Mitker]

@ikan:

Indeed. Airborne contamination is expected (and already felt / smelled - literally) according to winds but there is very little we can do about it.. except by covering our reservoir but this is going too far for what is primarily a security water reserve. We are currently building a green wall (read thick live bamboo fence - they can reach around 10M high) to partially address this issue

The reservoir area has been dug and we see on average 1 cubic meter per day of near surface (less than 3M) water infiltrating from the nearby grounds and we are just 20M from the first chemically boosted paddy. I wouldn't overlook what this water is carrying (soil here is quite porous)

No filtration is planned since the original purposes are (decreasing priority):

- secured supply for eventual fire-fighting needs

- light irrigation: keeping it green during the dry season

- supply for common industrial and cleaning needs (low)

- water for (non drinking) human use : here -yes- a local filtering equipment would process this specific part

- fish breeding is a way to make a useful use of this otherwise necessary installation

@pacificperson:

Thanks for these interesting tips